Liquid composition, recording method, and recorded matter

ABSTRACT

A liquid composition for agglutinating particles having a negative charge which are dispersed in a dispersion liquid, the liquid composition including: an organic acid ammonium salt represented by Formula (1), and water, Formula (1) where R 1  represents a hydroxyl group, a methyl group or a hydrogen atom; and R 2  represents a hydroxyl group or a methyl group.

TECHNICAL FIELD

The present invention relates to a liquid composition for makingparticles which are dispersed in a dispersion liquid and have a negativecharge on surfaces thereof agglutinate.

BACKGROUND ART

In recent years, in accordance with demands for recording a color imageat cheap cost, inkjet recording methods, in which a plurality ofdifferent color inks are provided to recording medium (referred to as“recording medium” hereinbelow) having no coating layer, such as regularpaper, to thereby record an image on the recording medium, are used. Inthis case, since the inks are provided to the recording medium having nocoating layer, the inks are directly absorbed into paper serving as thebase of the recording medium, and thus degradation in quality of therecording medium (referred to as “recorded matter” hereinbelow) which isrecorded by ink bleeding easily occur.

Then, it can be considered that an image is recorded using an ink havinglow permeability to prevent the ink from penetrating through therecording medium and to thereby prevent bleeding (referred to as“feathering” hereinbelow) at a boundary portion between the recordingmedium and the ink in the recorded matter. However, in this case, theink easily retains on a surface of the recording medium, andaccordingly, the drying properties of the recorded matter degrade. Whenthe drying properties of a recorded matter degrade, a finger or the likecomes into contact with an ink that has not yet been dried to causesmear on images, and in the case where a color image is recorded, adifferent color ink is attached to the ink that has not yet been dried,and bleeding (referred to as “color bleeding” hereinbelow) occurs at aboundary portion between these inks. Meanwhile, when an ink having highpermeability is used to prevent the occurrence of color bleeding, thereis a problem that the above-noted feathering occurs and the quality of aresulting recorded matter degrades.

To simultaneously solve these problems, there has been proposed arecording method using an ink and a liquid composition for fixing theink on a recording medium. For example, there has been proposed aninkjet recording method in which a reaction liquid containingpolyallylamine and an ink composition which contains a colorant and aresin emulsion is made adhere to a surface of a recording medium tothereby perform recording (see PTL 1 describes that according to thismethod, print bleeding and printing nonuniformity can be reduced on arecording medium and further, color bleeding can be effectivelyprevented. However, this proposal has a problem in terms of fixabilityof the ink composition on a recording medium. In other words, when theink composition is made to adhere to a surface of the recording mediumon which the liquid composition has been made to adhere, the pigment andthe resin emulsion contained in the ink come into contact withpolyallylamine which is positively charged, and rapidly agglutinate, andthus aggregates containing a small amount of vehicle (which means aliquid component in the reaction liquid or the ink composition) areaccumulated on the outermost surface layer of the recording medium. Theaccumulated layer is weak in resistance to abrasion (referred to as“abrasion resistance” hereinbelow”, and therefore, such a problem occursthat the rear surface of the recorded matter may be smeared with user'shand or ink. In addition, after an image recorded by this inkjetrecording method was analyzed, it was found that the diameter of dotsrecorded was small. This can be considered due to a strong effect of thereaction liquid which causes the ink to agglutinate. When the diameterof dots is excessively small, there is a problem that white streaks(which means portions where no ink adheres) occur.

To solve the problem with abrasion resistance, there has been proposedan inkjet recording method in which an ink and a liquid compositioncontaining specific polymer fine particles are made to adhere to asurface of a recording medium to thereby perform recording (see PTL 2).This proposal describes that it is possible to improve the abrasionresistance of recorded portions, because polymer fine particlescontained in the liquid composition covers pixels of the ink.

CITATION LIST Patent Literature

PTL 1 Japanese Patent (JP-B) No. 3206797

PTL 2 International Patent Publication No. 00/06390

SUMMARY OF INVENTION Technical Problem

However, the proposal using polymer fine particles has a problem interms of stability of the liquid composition. In other words, to fix anink by polymer fine particles, a large amount of polymer fine particlesare required. There is a problem in that a liquid composition containinga large amount of polymer fine particles, however, easily increased inviscosity, and in accordance with an increase in viscosity, thedischarge stability and storage stability of the liquid compositiondegrade.

The present invention aims to solve the above-mentioned conventionalproblems and to achieve the following object. That is, the presentinvention aims to provide a liquid composition which can preventoccurrence of feathering, color bleeding, white spots and strikethroughand has excellent fixability, abrasion resistance and drying properties,a recording method using the liquid composition and a recorded matterobtained by the recording method.

Solution to Problem

Means for solving the above-mentioned problems are as follows:

<1> A liquid composition for agglutinating particles having a negativecharge which are dispersed in a dispersion liquid, the liquidcomposition including;

an organic acid ammonium salt represented by Formula (1), and

water,

where R₁ represents a hydroxyl group, a methyl group or a hydrogen atom;and R₂ represents a hydroxyl group or a methyl group.

<2> The liquid composition according to <1>, wherein the organic acidammonium salt is ammonium lactate.

<3> The liquid composition according to one of <1> and <2>, furtherincluding:

a water-soluble polymer having a cationic functional group.

<4 > The liquid composition according to <3>, wherein the water-solublepolymer having a cationic functional group is a polyamine derivative ora polyamide derivative.

<5> The liquid composition according to any one of <1> to <4>, whereinthe liquid composition has a surface tension of 30 mN/m or lower.

<6> The liquid composition according to any one of <1> to <5>, furthercomprising:

a fluorine-based surfactant, and

a compound represented by Formula (2),

HOR₁R₃C—[CH₂]_(n)—CR₂R₄OH   Formula (2)

where R₁ and R₂ each independently represent an alkyl group having 3 to6 carbon atoms; R₃ and R₄ each independently represent an alkyl grouphaving 1 to 2 carbon atoms; and n is an integer of 1 to 6.

<7> A recording method including:

making the liquid composition according to any one of <1> to <6> adhereonto a recording medium, and

making an ink adhere onto the recording medium onto which the liquidcomposition has been made to adhere,

wherein the ink is a dispersion liquid in which particles containing acolorant and having a negative charge is dispersed in water.

<8> The recording method according to <7>, wherein the colorant is atleast one selected from the group consisting of a self-dispersiblepigment, a pigment coated with a resin, and a pigment dispersed by adispersant.

<9> A recorded matter including:

an image,

wherein the image is recorded by the recording method according to oneof <7> and <8>.

Advantageous Effects of Invention

When an ink is made to adhere onto a recording medium to which a liquidcomposition of the present invention adheres, a vehicle contained in theink is rapidly diffused by the effect of an organic acid ammonium saltcontained in the liquid composition, and at the same time, a colorantcontained therein agglutinates. With the occurrence of diffusion of thevehicle and agglutination of the colorant, the colorant is fixed at ashallow portion inside the recording medium, and thus it is possible toprevent occurrence of feathering and color bleeding and to obtain anexcellently fixed recorded matter.

According to the present invention, it is possible to solve theabove-mentioned conventional problems and achieve the object describedabove. More specifically, the present invention can provide a liquidcomposition which can prevent occurrence of feathering, color bleeding,white spots and strikethrough and has excellent fixability, abrasionresistance and drying properties, a recording method using the liquidcomposition, and a recorded matter obtained by the recording method.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating a state of arecorded portion in a recorded matter according to the presentembodiment.

FIG. 2 is a cross-sectional side view illustrating one example of anapparatus for use in a recording method according to the presentembodiment.

FIG. 3 is a cross-sectional side view illustrating another example ofthe apparatus for use in a recording method according to the presentinvention.

DESCRIPTION OF EMBODIMENTS (Liquid Composition)

A liquid composition according to the present invention is a liquidcomposition for agglutinating particles having a negative charge in adispersion liquid in which the particles are dispersed, and contains anorganic acid ammonium salt, and water, preferably further contains awater-soluble polymer having a cationic functional group, and asrequired, further contains other components.

Here, as for the “dispersion liquid in which particles having a negativecharge are dispersed”, for example, there may be preferably exemplifiedan ink which is a dispersion liquid in which particles containing acolorant and having a negative charge on their surfaces are dispersed.

Hereinafter, with reference to preferred embodiments, the liquidcomposition of the present embodiments will be further described indetail. The liquid composition of the present embodiment contains apredetermined organic aid ammonium salt and water, and thereby theparticles containing a colorant, which is to be dispersed in an ink, andhaving a negative charge on their surfaces are made to agglutinate. Anexpected mechanism of fixation of the ink using the liquid compositionof the present invention is described using a schematic cross-sectionalview for describing a stage of a recorded portion of a recorded matterof the present embodiment illustrated in FIG. 1. The liquid compositionof the present invention contains a lactic acid ion formed by dissolvinglactic acid ammonium in water, and an ammonium ion, and the like. Whenthe liquid composition is applied to a recording medium 101 made of apaper body, a liquid composition-attached portion 102 is formed on therecording medium 101. In the case where an ink containing a colorant andhaving a negative charge on its surface is applied onto the liquidcomposition-attached portion 102, a lactic acid ion and a weak acidammonium ion, which are weak base chelates and contained in the liquidcomposition-attached portion 102, act so that the concentration ofhydrogen ions and metal ions contained in the ink do not greatly vary(buffering action). For this reason, the colorant contained in the inksharply agglutinates (acid precipitation) due to an acid/base reaction,and the colorant in a large amount is prevented from precipitating onthe recording medium. As a result of this, a vehicle diffuses in adirection of the surface or inside of the recording medium, the area ofdots recorded is increased, and thereby the density of an image (whichincludes characters, symbols etc.) is increased. Subsequently, when anink 103 penetrates into the liquid composition-attached portion 102 ofthe recording medium 101, a colorant 104 contained in the ink 103 losesits dispersibility by the action of a lactic acid ammonium salt(including ions formed) contained in the liquid composition-attachedportion 102 to agglutinate (salting-out). The colorant 104 is fixed at ashallow position inside the recording medium in this way, thereby thefixability is improved, and the occurrence of feathering and colorbleeding is reduced.

It is desired that the liquid composition of the present embodiment bequickly absorbed into a recording medium after being applied to therecording medium, and be in a dried state in appearance. In order toaccomplish the objective, the surface tension of the liquid compositionis preferably 30 mN/m or lower. Note that it is enough for the liquidcomposition to in a dried state in appearance, and there is no need thata liquid such as water be vaporized to be unable to keep the liquidstate (in the present invention, this state is referred to as“solidification”). When the liquid composition penetrates into arecording medium and is in a dried state in appearance and even when theliquid composition is not solidified, it is possible to fix the ink andto improve the quality of an image to be recorded. Next, individualcomponents contained the liquid composition of the present embodimentwill be described hereinbelow.

<Organic Ammonium Salt>

As an organic ammonium salt for use in the liquid composition of thepresent invention, an organic ammonium salt represented by Formula (1)is used for the reasons of solubility to water, balance of the extent ofacidity or basicity of individual ions dissociated, ease of formingchelates, etc. The number of carbon atoms of the organic ammonium saltis not particularly limited, however, from the viewpoint of solubilityto water, it is preferably 6 per molecule or less. The organic ammoniumsalt is not particularly limited and may be suitably selected inaccordance with the intended use. It is, however, preferably a lacticacid ammonium salt. The addition amount of the organic ammonium salt ispreferably 1% by mass to 40% by mass, and more preferably 3% by mass to30% by mass, relative to the total amount of the liquid composition.When the addition amount is more than 40% by mass, the effect ofimproving the quality of a recorded image in commensurate with theincreased addition amount may not change, and the viscosity of theliquid composition may increase. When the addition amount is less than1% by mass, there is a potential that the effect of improving thequality of an image is reduced.

In Formula (1), R₁ represents a hydroxyl group, a methyl group or ahydrogen atom; and R₂ represents a hydroxyl group or a methyl group.

<Water-Soluble Polymer Having Cationic Functional Group>

A water-soluble polymer having a cationic functional group for use inthe liquid composition of the present invention is not particularlylimited. Examples thereof include water-soluble cationic polymers suchas a polyallylamine derivative, a polydiallylamine derivative, and apolyamide derivative. Specific examples of the water-soluble cationicpolymer include polymers containing a structural unit ofN,N-dialkylallylamine represented by Formula (C-1) or addition saltsthereof; polymers containing a structural unit of a N-substituted orunsubstituted diallylamine represented by Formula (C-2) or Formula (C-3)or addition salts thereof; and copolymers containing a repeating unitrepresented by (C-1) and a structural unit represented by Formula (C-2)or Formula (C-3) or addition salts thereof.

In Formula (C-1), R₁ and R₂ each independently represent an alkyl grouphaving 1 to 4 carbon atoms.

In Formulae (C-2) and (C-3), R₃ represents a hydrogen atom or an alkylgroup that may have 1 to 3 carbon atoms.

Among the copolymers, preferred is a copolymer which is obtained bycopolymerizing a N-substituted or unsubstituted diallylamine representedby Formula (C-2) or Formula (C-3) with N,N-dialkylallylamine representedby Formula (C-1) in an equimolar ratio or less. In addition, in thewater-soluble polymer having a cationic functional group (here,including the copolymer), the N,N-dialkylallylamine and theN-substituted or unsubstituted diallylamine may each be individuallyused alone or in combination of two or more. The weight averagemolecular weight of the water-soluble polymer having a cationicfunctional group is preferably 250 to 3,000 in a free state. Theignition residue of the water-soluble polymer having a cationicfunctional group is 5% by mass or less, preferably 2% by mass or less,and more preferably 0.5% by mass. Especially, the water-soluble cationicpolymer is preferably a copolymer of N,N-dialkylallylamine and aN-substituted or unsubstituted diallylamine having a residual monomeramount of 250 mass ppm or lower or addition salts thereof.

Other specific examples of the water-soluble cationic polymer include anaddition salt of a polymer containing a structural unit ofN,N-dialklallylamine represented by Formula (C-4) or Formula (C-5); anda copolymer containing a structural unit represented by Formula (C-4) orFormula (C-5) and a structural unit of polyamide represented by Formula(C-6) or a structural unit of polyallylamine represented by Formula(C-7). The copolymer preferably has a molar ratio of the structural unitof N,N-dialklallylamine represented by Formula (C-4) or Formula (C-5) tothe structural unit of polyamide represented by Formula (C-6) or thestructural unit of polyallylamine represented by Formula (C-7) of from95:5 to 50:50 and a weight average molecular weight of 2,000 to 15,000.

In Formulae (C-4) and (C-5), R₄ and R₅ may be identical to or differentfrom each other, and each represent an alkyl group having 1 to 4 carbonatoms; and X⁻ represents a counter ion selected from Cl⁻, Br⁻, and I⁻.

In Formulae (C-6) and (C-7), R₆ represents a hydrogen atom or a methylgroup.

Preferred example of other water-soluble cationic polymers include anaddition salt of a polymer containing a structural unit ofN,N-dialkylallylamine having an SO₂ group, which is represented byFormula (C-8). The weight average molecular weight of the polymer ispreferably 2,000 to 30,000.

In Formula (C-8), R₇ and R₈ may be identical to or different from eachother, and each represent an alkyl group having 1 to 4 carbon atoms; X⁻represents a counter ion selected from Cl⁻, Br⁻, and I⁻.

Further, as the water-soluble cationic polymer, a quaternary ammoniumsalt type cationic polymer, a water-dispersible cationic polymer and thelike are suitably used. The addition amount of the water-solublecationic polymer is preferably 1% by mass to 40% by mass of the liquidcomposition according to the present invention, and more preferably 3%by mass to 30% by mass. When the addition amount is more than 40% bymass, not only the effect of improving the quality of a recorded imageis reduced in commensurate with the increased addition amount but alsothe viscosity of the liquid composition may increase. When the additionamount is less than 1% by mass, there is a probability that the effectof improving the quality of a recorded image is reduced.

<Water-Soluble Organic Solvent>

The water-soluble organic solvent for use in the liquid compositionaccording to the present invention is used for retaining water containedin the liquid composition.

With use of the water-soluble organic solvent, an increase in viscosityof the liquid composition can be suppressed and the discharge stabilitycan be maintained, even when the liquid composition dries in a nozzlefor providing thereof or in a coater to reach a state of equilibriumwater content. For this reason, as the water-soluble organic solvent, itis preferable to use a water-soluble organic solvent havinghigh-equilibrium water content. Here, the equilibrium water contentmeans a water content when a mixture of a water-soluble organic solventand water is released in the air at a constant temperature and aconstant humidity, the evaporation of water in the solution and theabsorption of water in the air into the ink is in an equilibriumcondition. In the present embodiment, the water content equilibrium isdetermined as follows: a petri dish in which the water-soluble organicsolvent is weighed in an amount of 1 g is stored for a period until themass thereof does not change, in a desiccator in which the temperatureand humidity are maintained at 23° C.±1° C. and 80%±3% using a saturatedpotassium chloride aqueous liquid, and the water content equilibrium isdetermined by the following equation.

Equilibrium Water Content (wt %)=(Amount of water absorbed intowater-soluble organic solvent)+(Amount of water-soluble organicsolvent+Amount of water absorbed into water-soluble organic solvent)×100

Examples of the water-soluble organic solvent for use in the liquidcomposition according to the present embodiment include polyhydricalcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol arylethers, nitrogen-containing heterocyclic compounds, amides, amines,sulfur-containing compounds, propylene carbonate, and ethylenecarbonate. As a water-soluble organic solvent preferably used in thepresent embodiment, there may be exemplified a water-soluble organicsolvent having an equilibrium water content of 30% by mass or more underthe environment of 23° C. and 80% RH (which is referred to as“water-soluble organic solvent A”, hereinbelow), and a water-solubleorganic solvent having such an equilibrium water content of 40% by massor more.

As the water-soluble organic solvent A, polyhydric alcohols arepreferably used. Specific examples thereof include 1,2,3-butanetriol(atmospheric pressure (described only when the atmospheric pressure isnot 1 hPa, measured at (bp (boiling point) 175° C./bp): 33 hPa;equilibrium water content: 38% by mass), 1,2,4-butanetriol (bp: 190° C.to 191° C./24 hPa; 41% by mass), glycerin (bp: 290° C.; 49% by mass),diglycerin (bp: 270° C./20 hPa; 38% by mass), triethylene glycol (bp:285° C.; 39% by mass), tetraethylene glycol (bp: 324° C. to 330° C.; 37%by mass), diethylene glycol (bp: 245° C.; 43% by mass), 1,3-butanediol(bp: 203° C. to 204° C.; 35% by mass). Among these, glycerin, and1,3-butanediol are particularly preferably used because they show a lowviscosity when they contain water and can be stably maintained withoutcausing the colorant to agglutinate. When the water-soluble organicsolvent A is used in an amount of 50% by mass relative to the totalamount of water-soluble organic solvents, it is preferable in that thedischarge stability of the liquid composition can be improved, andfixing of the liquid composition on a recording apparatus can beprevented.

In the liquid composition according to the present embodiment, awater-soluble organic solvent having an equilibrium water content ofless than 30% by mass at 23° C. and 80% RH (which is referred to as“water-soluble organic solvent B” hereinbelow) may be used instead ofthe water-soluble organic solvent A or in addition to the water-solubleorganic solvent A. Examples of the water-soluble organic solvent Binclude polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydricalcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides,amines, sulfur-containing compounds, propylene carbonate, ethylenecarbonate, and other water-soluble organic solvents.

Specific examples of the polyhydric alcohols for the water-solubleorganic solvent B include dipropylene glycol (bp: 232° C.),1,5-pentanediol (bp: 242° C.), 3-methyl-1,3-butanediol (bp: 203° C.),propylene glycol (bp: 187° C.), 2-methyl-2,4-pentanediol (bp: 197° C.),ethylene glycol (bp: 196° C. to 198° C.), tripropylene glycol (bp: 267°C.), hexylene glycol (bp: 197° C.), polyethylene glycol(viscosity-adjusted liquid to solid), polypropylene glycol (bp: 187°C.), 1,6-hexanediol (bp: 253° C. to 260° C.), 1,2,6-hexanetriol (bp:178° C.), trimethylol ethane (solid, mp (melting point): 199° C. to 201°C.), and trimethylol propane (solid, mp: 61° C.).

Examples of the polyhydric alcohol alkyl ethers for the water-solubleorganic solvent B include ethylene glycol monoethyl ether (bp: 135° C.),ethylene glycol monobutyl ether (bp: 171° C.), diethylene glycolmonomethyl ether (bp: 194° C.), diethylene glycol monoethyl ether (bp197° C.), diethylene glycol monobutyl ether (bp: 231° C.), ethyleneglycol mono-2-ethylhexyl ether (bp: 229° C.), and propylene glycolmonoethyl ether (bp: 132° C.).

Examples of the polyhydric alcohol aryl ethers for the water-solubleorganic solvent B include ethylene glycol monophenyl ether (bp: 237°C.), and ethylene glycol monobenzyl ether

Examples of the nitrogen-containing heterocyclic compound for thewater-soluble organic solvent B include 2-pyrrolidone (bp: 250° C., rap:25.5° C., 47% by mass to 48% by mass), N-methyl-2-pyrrolidone (bp: 202°C.), 1,3-dimethyl-2-imidazolidinone (bp: 226° C.), ε-caprolactam (bp:270° C.), and γ-butylolactone (bp: 204° C. to 205° C.).

Examples of the amides for the water-soluble organic solvent B includeformamide (bp: 210° C.), N-methylformamide (bp: 199° C. to 201° C.),N,N-dimethylformamide (bp: 153° C.),and N,N-diethylformamide(bp: 176° C.to 177° C.).

Examples of the amines for the water-soluble organic solvent B includemonoethanolamine (bp: 170° C.), diethanolamine (bp: 268° C.),triethanolamine (bp: 360° C.), N,N-dimethylmonoethanolamine (bp: 139°C.), N-methyldiethanolamine (bp: 243° C.), N-methylethanolamine (bp:159° C.), N-phenylethanolamine (bp: 282° C. to 287° C.), and3-aminopropyldiethylamine (bp: 169° C.).

Examples of the sulfur-containing compounds for the water-solubleorganic solvent B include dimethylsulfoxide (bp: 139° C.), sulfolane(bp: 285° C.), and thiodiglycol (bp: 282° C.).

As for the other solid water-soluble organic solvents for thewater-soluble organic solvent B, sugar and the like are preferable.

Examples of the sugar include monosaccharides, disaccharides,oligosaccharides (including trisaccharides, and tetrasaccharides), andpolysaccharides. Specific examples of the sugar include glucose,mannose, fructose, ribose, xylose, arabinose, galactose, maltose,cellobiose, lactose, sucrose, trehalose, and malttriose. Here, the tern“polysaccharides” means a saccharide in a broad sense, and is usedherein it encompasses substances which are broadly present in naturesuch as a-cyclodextrin, and cellulose. In addition, as derivatives ofthese sugars, there may be exemplified reducing sugars of theabove-mentioned sugars (e.g., sugar alcohol represented by Formula:HOCH₂(CHOH)_(n)CH₂OH (where n is an integer of 2 to 5), acid sugar(e.g., aldonic acid, and uronic acid), amino acid, and thio acid. Amongthese, sugar alcohol is preferable. Specific examples of the sugaralcohol include maltitol, and sorbitol.

The amount of the water-soluble organic solvent contained in the liquidcomposition is not particularly limited. It is usually 10% by mass to80% by mass, and more preferably 15% by mass to 60% by mass. When thewater-soluble organic solvent content is more than 80% by mass, there isa probability that the drying properties of a recording medium to whichthe liquid composition has been made to adhere degrade. When thewater-soluble organic solvent content is less than 10% by mass, watercontained in the liquid composition easily vaporizes, and the viscosityof the liquid composition is increased as vaporization proceeds, whichmay lead to a failure in the coating step.

<Other Components>

Next, other components to be added to the liquid composition accordingto the present embodiment will be described. The liquid compositionaccording to the present embodiment contains an organic acid ammoniumsalt and water, and may additionally contain a surfactant, a penetrant,an anti-foaming agent, and the like.

<<Surfactant>>

The liquid composition according to the present embodiment may contain asurfactant for improving the wetting properties of a recording medium;the image density and color saturation of a recorded matter, preventingwhite spots (this means that blank portions remain in image portions ofa recorded matter), and for causing a vehicle in an ink speedilypenetrate into a recording medium to thereby improve the fixability. Inthis case, the amount of the surfactant is preferably 0.001% by mass to5% by mass, and more preferably 0.05% by mass to 2% by mass, relative tothe total amount of the liquid composition. When the surfactant contentis less than 0.001% by mass, the effect of adding the surfactant may bereduced, and when it is more than 5% by mass, it makes no difference ineffect obtained by increasing the addition amount thereof.

The surfactant is not particularly limited and may be suitably selectedin accordance with the intended use. Preferred examples of thesurfactant include fluorine-based surfactants, silicone-basedsurfactants, nonionic surfactants, anionic surfactants, andbetaine-based surfactants. Particularly preferred is at least oneselected from fluorine-based surfactants and silicone-based surfactants.These surfactants may be used alone or in combination.

—Fluorine-Based Surfactant—

The fluorine-based surfactant is not particularly limited and may besuitably selected in accordance with the intended use. Examples thereofinclude a perfluoroalkyl sulfonic acid compound, a perfluoroalkylcarboxylic acid compound, a perfluoroalkyl phosphate ester compound, aperfluoroalkylethylene oxide adduct, and a polyoxyalkylene ether polymercompound having a perfluoroalkyl ether group in the side chain. Amongthese, a fluorine-based surfactant having a perfluoroalkyl group ispreferable. A fluorine-based surfactant represented by the followingFormulae (F-1) to (F-4) is particularly preferable.

In addition, as the fluorine-based surfactant, a fluorine-basedsurfactant having 2 to 16 carbon atoms substituted with fluorine ispreferable, and a fluorine-based surfactant having 4 to 16 such carbonatoms is more preferable. When the number of carbon atoms substitutedwith fluorine is less than 2, the effect of using the fluorine-basedsurfactant may not be obtained, and when it is more than 16, it maycause a problem with storage stability.

C_(n)F_(2n+1)—CH₂CH(OH)CH₂O—(CH₂CH₂O)_(a)—Y′  Formula (F-1)

In Formula (F-1), n is an integer of 2 to 6; a is an integer of 15 to50, and Y′ represents —C_(b)H_(2b+1) (b is an integer of 11 to 19) or—CH₂CH(OH)CH₂—C_(d)F_(2d+1) (d is an integer of 2 to 6).

CF₃CF₂(CF₂CF₂)_(j)—CH₂CH₂O—(CH₂CH₂O)_(k)H   Formula (F-2)

In Formula (F-2), j is an integer of 0 to 10, and k is an integer of 0to 40.

In Formula (F-3), Rf represents a perfluoroalkyl group; m is an integerof 6 to 25; and n and p each represent an integer of 1 to 4.

In Formula (F-4), Rf represents a perfluoroalkyl group; X represents aquaternary ammonium group; an alkali metal such as sodium and potassium;triethylamine, or tri ethanolamine; Y represents —COO⁻, —SO₃ ⁻, —SO₄ ⁻,or —PO₄ ⁻; and q is an integer of 1 to 6.

Preferred examples of a compound represented by (F-1) are compounds eachrepresented by any one of the following structural formulae a) to u),for their high-ability to reduce a surface tension and their highpenetration properties. Among these, compounds represented by e), f),s), t) or u) are preferable because of their excellence in compatibilitywith an anti-foaming agent represented by the following formula (4).

C₄F₉—COO—(CH₂CH₂O)₂₃—C₁₂H₂₅   a)

C₄F₈—SO₂N(CH₃)—(CH₂CH₂O)₂₁—C₁₂H₂₅   b)

C₄F₉—CH₂CH₂O—CH₂CH₂O)₂₅—C₁₂H₂₅   c)

H(CF₂)₄—CH₂OCH₂CH(OH)CH₂O—(CH₂CH₂O)₂₁—C₁₄H₂₉   d)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₂₁—C₁₂H₂₅   e)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₂₅—C₁₂H₂₅   f)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₃₀—C₁₂H₂₅   g)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₂₀—C₁₄H₂₉   h)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₃₀—C₁₄H₂₉   i)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₂₃—C₁₆H₃₃   j)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₂₀—C₁₆H₃₃   k)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₂₅—C₆H₃₃   l)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₃₀—C₁₆H₃₃   m)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₄₀—C₁₆H₃₃   n)

C₄F₉—CH₂CH(OF)CH₂O—(CH₂CH₂O)₂₀—C₁₈H₃₇   o)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₃₀—C₁₈H₃₇   q)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₄₀—C₁₈H₃₇   r)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₂₃—CH₂CH(OF)CH₂—C₄F₉   s)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₃₅CH₂CH(OH)CH₂—C₄F₉   t)

C₄F₉—CH₂CH(OH)CH₂O—(CH₂CH₂O)₄₅—CH₂CH(OH)CH₂—C₄F₉   u)

In a compound represented by Formula (F-1) above, a(Hydrophile-Lipophile Balance) value determined by Griffin's method ispreferably 10 to 16 for the reason of the solubility in an aqueous ink.In addition, in the compound represented by Formula (F-1), a ratio of amolecular weight (MWEO) of a polyoxyethylene group [(CH₂CH₂O)_(a)portion] to a molecular weight (MWF) of a fluoroalkyl group(C_(n)F_(2n+1) portion and C_(m)F_(2m+1) portion) is preferably 2.2 to10 for the reason of balance between the functionality as a surfactantand the solubility in water.

In a compound represented by Formula (F-2) above, j is preferably aninteger of 0 to 10, and k is preferably an integer of 0 to 40. As forthe compound represented by (F-2) above, a commercially availablefluorine-based surfactant can be used. Examples of such commerciallyavailable surfactant include SURFRON S-111, S-112, S-113, S-121, S-131,S-132, S-141, and S-145 (all (produced by Asahi Glass Co.); FLUORADFC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431, andFC-4430 (all produced by Sumitomo 3M Ltd.); MEGAFACE F-470, F-1405, andF-474 (all produced by Dainippon Ink and Chemicals, Inc.); ZONYL FS-300,FSN, FSN-100, and FSO (all produced by DuPont); EFTOP EF-351, EF-352,EF-801, and EF-802 (all produced by Jemco Co.). Among these products,ZONYL FS-300, FSN, FSN-100, and FSO (all produced by DuPont) areparticularly preferable for their high reliability and excellence incolor saturation. These commercially products are each a mixture ofcompounds having several kinds of molecular weights, and in most case, jand k in Formula (F-2) have a distribution, however, in the presentembodiment, these commercially available products can be used withoutany problems.

In a compound represented by (F-3) Formula above, as Rf, aperfluoroalkyl group is preferably used for the reason of thefunctionality as a surfactant. As for the perfluoroalkyl group, the onehaving 1 to 10 carbon atoms is preferable, and the one having 1 to 3carbon atoms is more preferable. As such a perfluoroalkyl group, thoserepresented by —C_(n)F_(2n−1) (where n is an integer of 1 to 10) areexemplified. For example, —CF₃, —CF₂CF₃, —C₃F₇, and —C₄F₉ areexemplified. Among these perfluoroalkyl groups, —CF₃, and —CF₂CF₃ areparticularly preferable. In a compound represented by Formula (F-3), m,n, and p each represent an integer; n is an integer of 1 to 4; m is aninteger of 6 to 25; and p is preferably an integer of 1 to 4.

As Rf in a compound represented by Formula (F-4), a similarperfluoroalkyl group to that described in Formula (F-3) is preferablyused. For example, —CF₃, —CF₂CF₃, —C₃F₇, —C₄F₉ and the like arepreferably used. In a compound represented by Formula (F-4), Xrepresents a cation group. For example, quaternary ammonium group;alkali metals such as sodium, and potassium; triethylamine, andtriethanolamine are exemplified. Among these, quaternary ammonium groupis particularly preferable. In the compound represented by Formula(F-4), Y represents an anion group. Examples thereof include —COO⁻, —SO₃⁻, —SO₄ ⁻, and —PO₄ ⁻. In the compound represented by Formula (F-4), qrepresents an integer, for example, of 1 to 6.

As the at least one fluorine-based surfactant selected from thoserepresented by one of Formulae (F-3) and (F-4), a compound selected fromcompounds represented by one of Formulae (F-3-1) and (F-4-1) ispreferable from the viewpoint of safety.

In Formula (F-3-1), Rf represents —CF₃, or —CF₂CF₃; n represents aninteger of 1 to 4; m is an integer of 6 to 25; and p is an integer of 1to 4.

In Formula (F-4-1), Rf represents —CF₃, or —CF₂CF₃; and q is an integerof 1 to 6.

The amount of the fluorine-based surfactant contained in the liquidcomposition according to the present embodiment is preferably 0.01% bymass to 10% by mass, and more preferably 0.03% by mass to 5% by mass.When the amount of the fluorine-based surfactant is less than 0.01% bymass, an effect of color saturation visually observable may not beobtained, and an effect of causing a vehicle in the ink speedilypenetrate into a recording medium to improve the fixability may not beobtained. When the amount of the fluorine-based surfactant is more than10% by mass, the effect may not change even when the addition amountthereof is increased, and the fluorine-based surfactant may not bedissolved in a pretreatment liquid, and thus the physical properties ofthe resulting liquid may be unstable.

In the inkjet pretreatment liquid according to the present embodiment,the fluorine-based surfactants selected from Formulae (F-1) to (F-4) maybe used alone or in combination. Further, the fluorine-based surfactantmay be used in combination with a nonionic surfactant, an anionicsurfactant, an amphoteric surfactant, an acetylene glycol-basedsurfactant, or the like.

—Silicone-Based Surfactant—

The silicone-based surfactant is not particularly limited and may besuitably selected in accordance with the intended use. Examples of thesilicone-based surfactant include side-chain-modifiedpolydimethylsiloxane, both-terminal-modified polydimethylsiloxane,single-terminal-modified polydimethylsiloxane, andside-chain-both-terminal-modified polydimethylsiloxane. Apolyether-modified silicone-based surfactant having a polyoxyethylenegroup or a polyoxyethylene polyoxypropylene group is particularlypreferable, because it exhibits excellent properties as an aqueoussurfactant. The polyether-modified silicone-based surfactant is notparticularly limited and may be suitably selected in accordance with theintended use. Examples thereof include a compound in which apolyalkylene oxide represented by Formula (3) is introduced into Siportion side chain of dimethyl siloxane.

In Formula (3), m, n, a, and b each represent an integer; and R and R′each represent an alkyl group or an alkylene group.

As for such a silicone-based surfactant, a suitably synthesized one maybe used, and a commercially available product may be used. Such acommercially available product is available from BYK Chemie GmbH,Shin-Etsu Chemical Co., Ltd., TORAY Dow Corning Silicone Co., Ltd.,Nihon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd., etc. Examples ofspecific products of the polyether-modified silicone-based surfactantare KF-618, KF-642, and KF-643 (Shin-Etsu Chemical Co., Ltd.),EMALEX-SS-5602, and SS-1906EX (Nihon Emulsion Co., Ltd.), FZ-2105,FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, and FZ-2164 (TORAY DowCorning Silicone Co., Ltd.), BYK-33, and BYK-387 (BYK Chemie GmbH).

—Anionic Surfactant—

The anionic surfactant is not particularly limited and may be suitablyselected in accordance with the intended use. Examples of the anionicsurfactant include salts of polyoxyethylene alkylether acetate,dodecylbenzene sulfonate, laurate, and polyoxyethylene alkylethersulfate. Examples of the nonionic surfactant include polyoxyethylenealkylether, polyoxypropylene polyoxyethylene alkylether, polyoxyethylenealkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylenealkylphenyl ether, polyoxyethylene alkyl amine, and polyoxyethylenealkyl amide.

<<Penetrant>>

The liquid composition according to the present embodiment preferablycontains at least one kind of penetrant. Preferred examples of thepenetrant include non-wettable polyol compounds having 8 to 11 carbonatoms, and glycol ether compounds. Among these, preferred are thosehaving solubility from 0.2% by mass to 5.0% by mass in water at 25° C.,with 2-ethyl-1,3-hexanediol [solubility: 4.2% (25° C.)], and2,2,4-trimethyl-1,3-pentanediol [solubility: 2.0% (25° C.)] beingparticularly preferable.

Examples of other non-wettable polyol compound include fatty acid diolssuch as 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol,2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol,2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, and5-hexene-1,2-diol. Other penetrants usable in combination are notparticularly limited, as long as it can be dissolved in the liquidcomposition to thereby control physical properties of the liquidcomposition to desired physical properties, and may be suitably selectedin accordance with the intended use. Examples thereof include alkylethers and aryl ethers of polyhydric alcohols such as diethylene glycolmonophenyl ether, ethylene glycol monophenyl ether, ethylene glycolmonoallyl ether, diethylene glycol monophenyl ether, diethylene glycolmonobutyl ether, propylene glycol monobutyl ether, tetraethylene glycolchlorophenyl ether; and lower alcohols such as ethanol.

The amount of the penetrant contained in the liquid composition ispreferably 0.1% by mass to 5.0% by mass. When the amount of thepenetrant is less than 0.1% by mass, the effect of causing the liquidcomposition to penetrate into a recording medium may wear off. When theamount is more than 5.0% by mass, the penetrant segregates from thesolvent due to the low solubility of the penetrant, and thus the effectof improving the permeability of the liquid composition may besaturated.

<<Anti-Foaming Agent>>

The liquid composition according to the present embodiment may containan anti-foaming agent for the purpose of suppressing foaming (whichmeans that a liquid is formed into a thin film to enfold air).Generally, a liquid having high surface tension, like water, hardlyfoams because a force of reducing the surface area thereof as much aspossible works. Whereas a liquid having low surface tension and highviscosity easily foams, foams generated are retained and hardly removed.When the liquid composition according to the present embodiment containsthe above-mentioned water-soluble cationic polymer, water-solubleorganic solvent, surfactant and the like, the surface tension thereofdecreases and the viscosity thereof increases. For this reason, theliquid composition easily foams. To prevent this, an anti-foaming agentis preferably used therein.

In the present embodiment, when the liquid composition contains thefluorine-based surfactant, the surface tension of the liquid compositionis significantly reduced. In this case, an anti-foaming agent, which isa component insoluble in liquid, is used to intersperse this componentin the surface of foams, and thereby foaming can be usually suppressed.However, such a component insoluble in liquid degrades dischargestability and storage stability. In the present embodiment, to preventthis problem, when the liquid composition contains a fluorine-basedsurfactant, an anti-foaming agent represented by Formula (4) isfavorably used. The anti-foaming agent represented by Formula (4) hashigh compatibility with fluorine-based surfactants, and the anti-foamingagent is efficiently incorporated into a foamed film. It can beconsidered that for this reason, the surface of the foamed film islocally in an imbalance condition due to a difference in surface tensionbetween the fluorine-based surfactant and the anti-foaming agent, andfoams are broken.

HOR₁R₃C—[CH₂]_(n)—CR₂R₄OH   Formula (4)

In Formula (4), R₁ and R₂ each independently represent an alkyl grouphaving 3 to 6 carbon atoms; R₃ and R₄ each independently represent analkyl group having 1 to 2 carbon atoms; and n is an integer of 1 to 6.

The anti-foaming agent represented by Formula (4) is not particularlylimited and may be suitably selected in accordance with the intendeduse. However, 2,4,7,9-tetramethyldecane-4,7-diol, and2,5,8,11-tetramethyldodecane-5,8-diol are preferable, and from theviewpoints of anti-foaming effect and high solubility in the liquidcomposition, 2,5,8,11-tetramethyldodecane-5,8-diol is particularlypreferable.

The amount of the anti-foaming agent contained in the liquid compositionis preferably 0.01% by mass to 10% by mass, and more preferably 0.02% bymass to 5% by mass. When the amount of the anti-foaming agent is lessthan 0.01% by mass, the anti-foaming effect may not be sufficientlyobtained. When it is more than 10% by mass, the anti-foaming effect maynot change even when the addition amount thereof is increased, and theanti-foaming agent may not be dissolved in the liquid composition.

(Other Components)

The liquid composition according to the present embodiment may containan antiseptic agent, an anti-corrosive agent etc, used in a typical ink,as required.

[Ink]

Next, a recording method according to the present embodiment will bedescribed. The ink for use in the recording method of the presentembodiment contains particles containing a colorant and having negativecharges on their surfaces, and water. With this, the particles aredispersed in the ink by electrostatic repulsion. The color of the ink isnot particularly limited and may be suitably selected in accordance withthe intended use. Yellow, magenta, cyan, black and the like areexemplified. When recording is performed using an ink set in which twoor more of these color inks, a color image can be recorded. Whenrecording is performed using an ink set using at least three color inksin combination, a full color image can be recorded.

The ink is suitably used in an inkjet recording method using a recordingapparatus such as a so-called piezo-type recording apparatus (seeJapanese Patent Application Laid-Open (JP-A) No. 02-51734), a so-calledthermal type recording apparatus (see Japanese Patent ApplicationLaid-Open (JP-A) No. 61-59911), and a so-called electrostatic typerecording apparatus (see Japanese Patent Application Laid-Open (JP-A)No. 06-71882). Also, the ink is suitably used in a recording apparatushaving a function to heat a recording medium and ink in recording orbefore or after recording to accelerate fixing of a recorded matter.Further, the ink is also used in a recording apparatus which heats arecording medium and ink in recording or before or after recording to,for example, from 50° C. to 200° C. to accelerate fixing of a recordedmatter.

Physical properties of the ink of the present embodiment are notparticularly limited and may be suitably selected in accordance with theintended use. For example, the viscosity, and the surface tension of theink are each preferably within the following ranges. First, theviscosity of the ink at 25° C. is preferably 5 mPa·s to 20 mPa·s. Byadjusting the viscosity of the ink to 5 mPa·s or higher, the density andquality of an image to be recorded can be improved. Meanwhile, byadjusting the viscosity of the ink to 20 mPa·s or lower, excellentdischarge stability can be obtained. Here, the viscosity can be measuredusing a viscometer (e.g., RE-550L, manufactured by TOKI SANGYO Co.,Ltd.) at 25° C.

The surface tension of the ink at 25° C. is preferably 20 mN/m to 35mN/m, and more preferably 20 mN/m to 30 mN/m. When the surface tensionof the ink is from 20 mN/m to 35 mN/m, the permeability of the ink isenhanced, and even when the ink is recorded on regular paper, the dryingproperties are excellent, and thereby color bleeding can be suppressed.Further, the ink is easily wet in a liquid composition-attached portionof a recording medium (a portion of a recording medium onto which theliquid composition has been attached), the color saturation of aresulting recorded matter is increased, and the resistance to whitespots is also improved. When the surface tension is higher than 35 mN/m,the leveling of the ink (which means that an ink is uniformly spread ona surface of a recording medium while wetting the surface thereof)easily occurs on a recording medium, which may lead to lengthening ofdrying time of the ink. Next, individual components contained in the inkwill be described.

<Colorant >

In the ink, as a water-dispersible colorant, a pigment is mainly usedfrom the viewpoint of weatherability, however, to control the colortone, a dye may be used in combination within a range not degrading theweatherability. The pigment is not particularly limited and may besuitably selected in accordance with the intended use. For example, aninorganic pigment or organic pigment for black color ink or an inorganicpigment or organic pigment for color ink is used. These pigments may beused alone or in combination.

The amount of the water-dispersible colorant contained in the ink ispreferably, in terms of solid fraction, 2% by mass to 15% by mass, andmore preferably 3% by mass to 12% by mass. When the amount of thepigment is less than 2% by mass, the color saturation and image densityof a resulting recorded matter may decrease. When the amount of thepigment is more than 15% by mass, it is unfavorable because thedischarge stability may degrade due to the increased viscosity of theink. Here, the solid fraction content of the ink is measured, forexample, by a method of isolating only the water-dispersible colorantand the water-dispersible resin fraction from the ink. In addition, whena pigment is used as the water-dispersible colorant, a ratio between thecolorant and the water-dispersible resin is measured by determining amass reduction rate through thermal mass spectrometry. When themolecular structure of the water-dispersible colorant is clearly known,the solid fraction of a pigment or dye can be determined through NMR(Nuclear Magnetic Resonance). As for heavy metal atoms, an inorganicpigment contained in a molecular skeleton, a gold-containing pigment,and a gold-containing dye, the solid fraction of the colorant can bedetermined through X-ray fluorescence analysis.

As the inorganic pigment, there may be used an titanium oxide, ironoxide, calcium carbonate, barium sulfate, aluminum hydroxide, bariumyellow, cadmium red and chrome yellow; and carbon black produced by aconventionally known method such as a contact method, a furnace method,a thermal method or the like.

As the organic pigment, there may be used azo pigments (including azolake, insoluble azo pigment, condensed azo pigment, chelate azo pigment,etc.) polycyclic pigments (e.g., phthalocyanine pigment, perylenepigment, perynone pigment, anthraquinone pigment, quinacridone pigment,dioxazine pigment, indigo pigment, thioindigo pigment, isoindolinonepigment, and quinophthalone pigment), dye chelates (e.g., basic dye-typechelate, and acid dye-type chelate), nitro pigments, nitroso pigments,and aniline black. Among these pigments, those having excellent affinitywith water are particularly preferably used.

Specific examples of preferably usable black color pigments includecarbon black such as furnace black, lamp black, acetylene black, andchannel black, (C.I. Pigment Black 7), or metals such as copper, iron(C.I. Pigment Black 11), and titanium oxide, and organic pigments suchas aniline black (C.I. Pigment Black 1). Specific examples of preferablyusable color pigments include C.I. Pigment Yellow 1, 3, 12, 13, 14, 17,24, 34, 35, 37, and 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97,98, 100, 101, 104, 408, 109, 110, 117, 120, 128, 138, 150, 151, 153,183, C.I. Pigment Orange 5, 13, 16, 17, 36, 43, and 51, C.I. Pigment Red1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, and 48:2 (Permanent Red 2B(Ca)),48:3, 48:4, 49:1, 52:2, 53:1, and 57:1 (Brilliant Carmine 6B), 60:1,63:1, 63:2, 64:1, 81, 83, 88, and 101 (colcothar), 104, 105, 106, 108(Cadmium Red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166,168, 170, 172, 177, 178, 179, 185, 190, 193, 209, and 219, C.I. PigmentViolet 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, and 38, C.I. Pigment Blue1, 2, 15, 15:1, 15:2, 15:3 (phthalocyanine blue), 16, 17:1, 56, 60, 63,and C.I. Pigment Green 1, 4, 7, 8, 10, 17, 18, and 36.

In the present embodiment, the coloring material is dispersed asparticles having a negative charge, in water. In this case, as asub-embodiment of dispersing the pigment in water, there may bepreferably exemplified first to third sub-embodiments described below.In the first sub-embodiment, a dispersoid obtained by incorporating awater-insoluble or water-sparsely soluble coloring material into polymerfine particles (which may be referred to as “a pigment coated with aresin) is dispersed in water serving as a dispersion medium to produce apolymer emulsion (a water dispersion of polymer fine particlescontaining a coloring material). Note that in this case, part of thedispersoid contains solid fractions, and in the present embodiment, thisis referred to as “an emulsion”. In the second sub-embodiment, a pigmenthaving at least one hydrophilic group on its surface and showingwater-dispersibility in the absence of dispersants (the pigment is,otherwise, referred to as “a self-dispersible pigment) is dispersed inwater. In the third sub-embodiment, a pigment is dispersed in waterusing an anionic dispersant or a nonionic dispersant.

Examples of the polymer emulsion for use in the first sub-embodimentinclude a polymer emulsion in which a pigment is encapsulated in polymerfine particles or a pigment is adsorbed on surfaces of polymer fineparticles. In this case, the entire pigment is not necessarilyencapsulated in or adsorbed onto polymer fine particles, and it isallowable that the pigment is dispersed in the emulsion within a rangenot impairing the effects of the present embodiment. Examples of apolymer (polymer in polymer fine particles) forming the polymer emulsioninclude anionic vinyl polymers, polyester-based polymers, andpolyurethane-based polymers. Particularly preferably usable polymers arevinyl-based polymers and polyester-based polymers. Polymers disclosed inJapanese Patent Application Laid-Open (JP-A) Nos. 2000-53897,2001-139849 and the like can be used.

The self-dispersible pigment according to the second sub-embodiment is apigment in which at least one hydrophilic group is bonded, directly orvia another atomic group, to a surface of a pigment to modify thesurface of the pigment. To modify the surface of the pigment, there maybe used a method in which a predetermined anionic functional group (afunctional group such as a sulfone group and a carboxyl group) ischemically bonded to a surface of a pigment or a method in which apigment is subjected to a wet-process oxidation treatment using at leastone of a hypohalous acid or a salt thereof. Of these methods,particularly preferred is a sub-embodiment in which a carboxyl group isbonded to a surface of a pigment and the pigment is dispersed in water.When a carboxyl group is bonded to a surface of a pigment, not only thedispersion stability of the pigment is improved, but also a high qualityimage can be obtained, and the water resistance of a resulting recordedrecording medium is more improved. Further, an ink containing theself-dispersible pigment according to the second sub-embodiment isexcellent in re-dispersibility, and even when recording is stopped for along period of time and the water content of the ink filled in a nozzlein a recording apparatus is evaporated, excellent recording can beeasily performed with a simple cleaning operation, without causingnozzle clogging. To obtain such properties, the volume average particlediameter (D₅₀) of the self-dispersible pigment in the ink is preferably0.01 μm to 0.16 μm. Here, D₅₀ is also called a median diameter and meansa diameter in which, when a particle is divided into two at a portionhaving a certain particle diameter, a larger side and a smaller side arein equal parts (e.g. volume average particle diameter). Note that, inthe present embodiment, when a self-dispersible pigment according to thesecond sub-embodiment is used, the ink preferably contains awater-dispersed resin, which will be described below, for improving thefixability (abrasion resistance) of the colorant on a recording mediumand improving the color-developing ability.

When the self-dispersible pigment is a self-dispersible carbon black, asan anionic functional group to be bonded to the carbon black, there maybe exemplified —COOM, —SO₃M, —PO₃HM, —PO₃M₂, —SO₂NH₂, and —SO₂NHCOR(where M represents an alkali metal, ammonium or organic ammonium; and Rrepresents an alkyl group having 1 to 12 carbon atoms, a phenyl groupthat may have a substituent or a naphthyl group that may have asubstituent.). Among these, —COOM, and —SO₃M are preferable. When “M” inthe above-mentioned functional group is an alkali metal, for example,there may be used lithium, sodium, or potassium. When “M” is organicammonium, for example, there may be used monomethyl to trimethylammonium, monoethyl to triethyl ammonium or monomethanol to trimethanolammonium. The functional group may be bonded to a surface of carbonblack via other atomic groups. Examples of the other atomic groupsinclude an alkyl group having 1 to 12 carbon atoms, a phenyl group thatmay have a substituent or a naphthyl group that may have a substituent.Specific examples of the functional to be bonded on a surface of carbonblack via other atomic groups include —C₂H₄COOM (where M represents analkali metal or quaternary ammonium.), and —PhSO₃M (where Ph representsa phenyl group; and M represents an alkali metal or quaternaryammonium.).

When the self-dispersible pigment is a color pigment, theabove-mentioned anionic functional group (e.g., —COONa) can beintroduced into the color pigment by a method in which the color pigmentis subjected to an oxidation treatment using hypochlorous acid soda, amethod of sulfonating the color pigment, a method of reacting adiazonium salt with the color pigment or the like.

In the third sub-embodiment, the above-mentioned pigment is dispersed inwater by an anionic dispersant or a nonionic dispersant. Examples of theanionic dispersant include polyoxyethylene alkylether acetate, analkylbenzene sulfonic acid salt (NH₄, Na, Ca), an alkyldiphenyletherdisulfonic acid salt (NH₄, Na,Ca), a sodium salt of dialkylsuccinatesulfonate, a sodium salt of a naphthalene sulfonate-formalin condensate,an ester salt of a polyoxyethylene polycyclic phenylether sulfate(NH₄,Na), a lauric acid salt, a sulfate salt of polyoxyethylenealkylether, and an oleic acid salt. Among these, particularly preferablespecific examples of the anionic surfactant include a sodium salt ofdioctyl sulfosuccinate and a NH₄ salt of polyoxyethylene styrenephenylether sulfonate.

As the nonionic surfactant, a nonionic surfactant having an HLB value of10 to 20 is preferable. Examples thereof include polyoxyethylenealkylether, polyoxyalkylene alkyl ether, polyoxyethylene polycyclicphenyl ether, sorbitan fatty acid ester, polyoxyethylene alkyl phenylether, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, andacetylene glycol. Among these, particularly preferable specific examplesof the nonionic surfactant include polyoxyethylene lauryl ether,polyoxyethylene-β-naphthylether, polyoxyethylene sorbitan monooleate,and polyoxyethylene styrene phenyl ether. Note that, when a nonionicdispersant is used, the entire system of the ink can also be negativelycharged by using a negatively charged resin emulsion in combination.

In the third sub-embodiment, the pigment dispersion is produced in thefollowing method. First, the above-mentioned pigment dispersant isdissolved in an aqueous medium. Next, the organic pigment or theinorganic pigment is added thereto, and the system is sufficientlywetted, followed by high-speed stirring through use of a homogenizer, orstirring and dispersing through use of a dispersing machine using a ballsuch as a bead mill and a ball mill, a dispersion kneader using ashearing force such as a roll mill, a ultrasonic wave dispersingmachine, or the like. In most cases, coarse particles are contained inthe resulting pigment dispersion after such a kneading/dispersing step.This causes nozzle clogging and/or clogging of an ink-supply channel ina recording apparatus, and thus there is a need to remove particleshaving a particle diameter of 1 μm or greater using a filter or acentrifugal separator.

In the present embodiment, it is preferable that the dispersant be usedin an amount of 1% by mass to 100% by mass, and more preferably in anamount of 10% by mass to 50% by mass, relative to the amount of thepigment. When the amount of the dispersant is small, it is impossible toform the pigment into sufficiently fine particles. When the amount ofthe dispersant is excessively large, excess components of the dispersantnot adsorbed on the pigment adversely affect physical properties of theresulting ink, which may cause ink bleeding, and degradation of waterresistance and abrasion resistance of an image to be recorded. Note thatin the present embodiment, when the self-dispersible pigment accordingto the third sub-embodiment is used, the ink preferably contains awater-dispersed resin, which will be described below, for improving thefixability (abrasion resistance) of the colorant on a recording mediumand improving the color-developing ability.

Further, to stabilize the pigment dispersion, a water-soluble polymercompound having an average molecular weight of 30,000 or lower may beused in combination. As the water-soluble polymer compound, generally, awater-soluble styrene-acrylic resin, water-soluble polyurethane,water-soluble polyester, water-soluble styrene-maleic acid copolymer,and water-soluble a-olefin-maleic acid copolymer each having a molecularweight of 30,000 or lower are preferable. Among these, water-solublepolyurethane, water-soluble polyester, and a water-solublea-olefin-maleic acid copolymer represented by Formula (5) areparticularly preferable.

In Formula (5), R represents an alkyl group having 6 to 22 carbon atoms,and n is an integer of about 30 to about 100.

The acid value of the water-soluble a-olefin-maleic acid copolymerrepresented by Formula (5) is preferably 100 mgKOH/g to 400 mgKOH/g.When the acid value is lower than 100, the solubility of the pigmentdispersion may degrade. In contrast, when the acid value is higher than400, the viscosity of the pigment dispersion increases, and there is apotential that the ink-discharge properties easily degrade and thedispersion stability of the pigment dispersion easily degrades. Theweight average molecular weight of the water-soluble a-olefin-maleicacid copolymer represented by Formula (5) is preferably 5,000 to 20,000.When the weight average molecular weight is lower than 5,000, thedispersion stability of the pigment dispersion may degrade. In contrast,when the weight average molecular weight is higher than 20,000, thesolubility of the pigment dispersion may degrade, and the viscositythereof may increase.

The amount of the water-soluble polymer compound contained in thepigment is preferably 1% by mass to 100% by mass (in terms of solidfraction), and more preferably 5% by mass to 50% by mass. When theamount of the water-soluble polymer compound is less than 1% by mass,the effect of improving the dispersion stability may be insufficient. Incontrast, when the amount of the water-soluble polymer compound ishigher than 100% by mass, the viscosity of the ink increases, thedischarge stability thereof may degrade, and it may make no differencein the effect of improving the dispersion stability even when theaddition amount thereof is increased.

The volume average particle diameter (D₅₀) of the pigment of the presentembodiment is preferably 150 nm or smaller in an ink, and morepreferably 100 nm or smaller. When the volume average particle diameter(D₅₀) of the pigment is greater than 150 nm, the discharge stability ofthe resulting ink rapidly degrades, and nozzle clogging and ink ejectiondeviation easily occur. In contrast, when the volume average particlediameter (D₅₀) is 100 nm or smaller, the discharge stability isimproved, and the color saturation of an image is also improved. Theamount of the pigment in the ink is preferably about 1% by mass to about15% by mass, and more preferably about 2% by mass to about 12% by mass.Moreover, the polymer emulsion according to the first sub-embodiment inwhich a pigment is coated with anionic polymer fine particles, and theself-dispersible pigment according to the second sub-embodiment, and thewater-dispersible colorant according to the third sub-embodiment may beused in combination in the form of a mixture.

<Water-Soluble Organic Solvent>

As a water-soluble organic solvent for use in the ink, a similarwater-soluble organic solvent to that used in the liquid composition ispreferably used. The mass ratio of the water-dispersible colorant to thewater-soluble organic solvent in the ink influences the dischargestability of the ink discharged from an inkjet head. For example, whenthe amount of the water-soluble organic solvent is small although thesolid fraction of the water-dispersible colorant is high, evaporation ofwater present in the vicinity of an ink meniscus of a nozzle may proceedto cause a discharge defect. The amount of the water-soluble organicsolvent contained in the ink is preferably 20% by mass to 50% by mass,and more preferably 20% by mass to 45% by mass. When the water-solubleorganic solvent content is less than 20% by mass, there is a possibilitythat the discharge stability degrades and a waste ink adheres to amaintenance device in a recording apparatus. When the water-solubleorganic solvent content is more than 50% by mass, the drying propertiesthereof may degrade on a paper surface, and the quality of a recordedmatter may further degrade.

<Surfactant>

As a surfactant for use in the ink, a similar surfactant to that used inthe liquid composition of the present embodiment is preferably used.Among these preferably usable surfactants, it is preferable to select asurfactant having low surface tension and high permeability and highleveling properties, without impairing the dispersion stability of thepigment dispersion depending on the combination type of thewater-dispersible colorant and the water-soluble organic solvent used.Specifically, at least one selected from an anionic surfactant, anonionic surfactant, a silicone-based surfactant and a fluorine-basedsurfactant is preferably used. Among these, a silicone-based surfactantand a fluorine-based surfactant are particularly preferably used. Thesesurfactants may be used alone or in combination. The amount of thesurfactant contained in the ink is preferably 0.01% by mass to 3.0% bymass, and more preferably 0.5% by mass to 2% by mass. When thesurfactant content is less than 0.01% by mass, the effect obtained whenadding the surfactant may be insufficient, and whereas, when it is morethan 3.0% by mass, the permeability of the ink to a recording medium isincreased more than necessary, the image density of a recorded image maydegrade, and strikethrough (this means that the ink attached to arecording medium penetrates through the recording medium and isdistinguished from the rear surface of the recorded image) may occur.

<Penetrant>

A penetrant for use in the ink, a similar penetrant to that used in theliquid composition of the present embodiment is preferably used. Theamount of the penetrant contained in the ink is preferably 0.1% by massto 4.0% by mass. When the penetrant content is less than 0.1% by mass,the drying properties of the ink degrades, and ink bleeding may occur ina recorded image. When the penetrant content is more than 4.0% by mass,the dispersion stability of the colorant is impaired, nozzle cloggingmay easily occur in a recording apparatus, and the permeability of theink to a recording medium is increased more than necessary, which maycause a decrease in image density of a recorded matter andstrikethrough.

<Water-Dispersible Resin>

The above-mentioned water-dispersible resin is formed into a film on arecorded matter onto which the ink has been made to adhere, and is usedfor improving the water repellency, water resistance and weatherabilityof a recorded image and improving the image density and color saturationthereof. As for the water-dispersible resin, both a homopolymer and acomposite resin made of a copolymer may be used, and any of asingle-phase structured type emulsion, a core-shell type emulsion and apower-feed type emulsion may be used. In addition, as for thewater-dispersible resin, both a water-dispersible resin in which a resinitself has a hydrophilic group and self-dispersibility and awater-dispersible resin in which a resin itself does not havedispersibility and to which the dispersibility is imparted by asurfactant and a resin having a hydrophilic group may be used. Examplesof this water-dispersible resin include condensed type synthetic resins,addition type synthetic resins, and natural polymer compounds.

Examples of the condensed type synthetic resins include polyesterresins, polyurethane resins, polyepoxy resins, polyamide resins,polyether resins, poly(meth)acrylic resins, acryl-silicone resins, andfluorine-based resins. Examples of the addition type synthetic resinsinclude polyolefin resins, polystyrene-based resins, polyvinylalcohol-based resins, polyvinyl ester-based resins, polyacrylicacid-based resins, and unsaturated carboxylic acid-based resins.Examples of the natural polymer compounds include celluloses, rosins,and natural rubbers. Among these, polyurethane resin fine particles,acryl-silicone resin fine particles, and fluorine-based resin fineparticles are particularly preferable. These water-dispersible resinsmay be used in combination.

Here, as for the fluorine-base resin, fluorine-based resin fineparticles having a fluoroolefin unit are preferable. Among these,fluorine-containing vinylether-based resin fine particles composed of afluoroolefin unit and a vinylether unit are particularly preferable. Thefluoroolefin unit is not particularly limited and may be suitablyselected in accordance with the intended use. Examples thereof include—CF₂CF₂—, —CF₂CF(CF₃)—, and —CF₂CFCl—. The vinylether unit is notparticularly limited and may be suitably selected in accordance with theintended use. Examples thereof include compounds represented by each ofthe following structural formula.

As for the fluorine-containing vinylether-based resin fine particlescomposed of a fluoroolefin unit and a vinylether unit, an alternatecopolymer in which a fluoroolefin unit and a vinylether unit arealternately copolymerized is preferable. As such fluorine-based resinfine particles, suitably synthesized one and a commercially availableproduct may be used. Here, as commercially available products thereof,there may be exemplified FLUONATE FEM-500, FEM-600, DICGUARD F-52S,F-90, F-90M, F-90N and AQUAFURAN TE-5A produced by Dainippon InkChemical Industries Co., Ltd.; LUMIFLON FE4300, FE4500, FE4400, ASAHIGUARD AG-7105, AG-950, AG-7600, AG-7000, and AG-1100 produced by AsahiGlass Co., Ltd.

As the water-dispersible resin, a water-dispersible resin in which aresin itself has a hydrophilic group and self-dispersibility and awater-dispersible resin in which a resin itself does not havedispersibility and to which the dispersibility is imparted by asurfactant and a resin having a hydrophilic group are used. Of these, anemulsion of resin particles obtained by emulsification or suspensionpolymerization of an ionomer of a polyester resin, a polyurethane resinor an unsaturated monomer is preferably used. Here, when an unsaturatedmonomer is emulsion polymerized, a water-dispersible resin is easilyproduced because a resin emulsion is obtained by reacting water intowhich the unsaturated monomer, a polymerization initiator, a surfactant,a chain transfer agent, a chelating agent, a pH adjustor etc. have beenadded. In this case, a water-dispersible resin having intended physicalproperties can be easily produced because components constituting theresin are easily changed.

As for the unsaturated monomer, unsaturated carboxylic acids,monofunctional or polyfunctional (meth)acrylic acid ester monomers,(meth)acrylic acid amide monomers, aromatic vinyl monomers, vinyl cyanocompound monomers, vinyl monomers, allyl compound monomers, olefinmonomers, diene monomers, oligomers having an unsaturated carbon etc.can be used alone or in combination. The physical properties of awater-dispersible resin produced can be easily changed by using thesemonomers in combination. Further, the physical properties of the resincan also be modified by subjecting the components to a polymerizationreaction or graft reaction using, as a polymerization initiator, anoligomer type polymerization initiator.

Examples of the unsaturated carboxylic acids serving as the unsaturatedmonomer include an acrylic acid, methacrylic acid, itaconic acid,fumaric acid, and maleic acid.

Examples of the monofunctional (meth)acrylic acid ester monomers includemethyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butylmethacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamylmethacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, octylmethacrylate, decyl methacrylate, dodecyl methacrylate, octadecylmethacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzylmethacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate,2-hydroxypropyl methacrylate, dimethyl aminoethyl methacrylate,methacryloxy ethyl trimethyl ammonium salts, 3-methacryloxypropyltrimethoxysilane, methyl acrylate, ethyl acrylate, isopropyl acrylate,n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate,n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate,dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenylacrylate, benzyl acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate,2-hydroxypropyl acrylate, dimethyl aminoethyl acrylate, and acryloxyethyl trimethyl ammonium salts.

Examples of the polyfunctional (meth)acrylic acid ester monomers includeethylene glycol dimethacrylate, diethylene glycol dimethacrylate,triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate,1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate,1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate,dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate,polybutylene glycol dimethacrylate,2,2′-bis(4-methacryloxydiethoxyphenyl)propane, trimethylol propane trimethacrylate, trimethylol ethane tri methacrylate, polyethylene glycoldiacrylate, triethylene glycol diacrylate, 1,3-butylene glycoldiacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate,neopentyl glycol diacrylate, 1,9-nonanediol diacrylate, polypropyleneglycol diacrylate, 2,2′-bis(4-acryloxypropylenephenyl)propane,2,2′-bis(4-acryloxydiethoxyphenyl)propane trimethylol propanetriacrylate, trimethylolethane triacrylate, tetramethylolmethanetriacrylate, ditrimethylol tetraacrylate, tetramethylol methanetetraacrylate, pentaerythritol tetraacrylate, and dipentaerythritolhexaacrylate.

Examples of the (meth)acrylic acid amide monomers include acrylamide,methacrylamide, N,N-dimethyl acrylamide, methylene bis-acrylamide, and2-acrylamide-2-methylpropane sulfonic acid.

Examples of the aromatic vinyl monomers include styrene,α-methylstyrene, vinyl toluene, 4-t-butylstyrene, chlorostyrene, vinylanisole, vinyl naphthalene, and divinyl benzene.

Examples of the vinyl cyano compound monomers include acrylonitrile, andmethacrylonitrile.

Examples of the vinyl monomers include vinyl acetate, vinylidenechloride, vinyl chloride, vinyl ether, vinyl ketone, vinyl pyrrolidone,vinyl sulfonic acid or salts thereof, vinyl trimethoxysilane, and vinyltriethoxysilane.

Examples of the allyl compound monomers include allylsulfonic acid orsalts thereof, allylamine, allyl chloride, diallylamine, anddiallyldimethyl ammonium salts.

Examples of the olefin monomers include ethylene, and propylene.

Examples of the diene monomers include butadiene, and chloroprene.

Examples of the oligomers having an unsaturated carbon include styreneoligomers each having a methacryloyl group, styrene-acrylonitrileoligomers each having a methacryloyl group, methyl methacrylateoligomers each having a methacryloyl group, dimethyl siloxane oligomerseach having a methacryloyl group, and polyester oligomers each having anacrylonitrile group.

Since a water-dispersible resin undergoes dispersion breaking andbreaking of molecular chains due to hydrolysis, under a strong alkalineor strong acidic condition, the pH of the water-dispersible resin beforebeing prepared into an ink is preferably 4 to 12. Particularly, from theviewpoint of miscibility with a water-dispersible colorant, the pH is pHis more preferably 6 to 11, and still more preferably 7 to 9. Theaverage particle diameter (D₅₀) of the water-dispersible resin relatesto the viscosity of the dispersion liquid. When water-dispersible resinshaving the same composition and the same concentration of solidfraction, the smaller the particle diameter, the higher the viscosityis. Therefore, the average particle diameter (D₅₀) of thewater-dispersible resin is preferably 50 nm or greater so that theviscosity of the resulting ink is not excessively high. When theparticle diameter of the water-dispersible resin is several tenmicrometers, it is greater than the diameter of a nozzle of an inkjethead in a recording apparatus. When such particles having large particlediameters are present in the resulting ink, the discharge stability ofthe ink degrades. Then, to secure the discharge stability of the ink,the average particle diameter (D₅₀) of the water-dispersible resin ispreferably 200 nm or smaller, and more preferably 150 nm or smaller.

Further, since the water-dispersible resin has a function to fix awater-dispersible colorant on a recording medium, it is preferable toform it into a film at normal temperature. For this reason, the minimumfilm-forming temperature (MFT) of the water-dispersible resin ispreferably 30° C. or lower. In addition, when the glass transitiontemperature of the water-dispersible resin is lower than −40° C., theconsistency of the resin film is higher, and tacking (which meansstickiness, and viscosity) may occur on a recorded matter. For thisreason, the glass transition temperature of the water-dispersible resinis preferably −40° C. or higher, and more preferably −30° C. or higher.The amount of the water-dispersible resin contained in the ink ispreferably, in terms of solid fraction, 1% by mass to 15% by mass, andmore preferably 2% by mass to 7% by mass.

<Other Components>

Next, other components that can be added to an ink used in the recordingmethod of the present embodiment will be described. Such othercomponents are not particularly limited and may be suitably selected asrequired. Examples thereof include a pH adjustor, anantiseptic-antifungal agent, a chelating reagent, an anti-corrosiveagent, an antioxidant, a ultraviolet absorber, an oxygen absorbent, anda light stabilizer.

—pH Adjustor—

The pH adjustor is not particularly limited, as long as it can adjustthe pH of an ink formulated to 7 to 11 without adversely affecting theink, and may be suitably selected in accordance with the intended use.When the pH of the ink is lower than 7 or higher than 11, it melts downa head in a recording apparatus and a unit for supplying the ink, anddeteriorates the ink or leaks, and failures such as discharge defect mayoccur. Examples of the pH adjustor preferably used in the presentembodiment include alcohol amines, hydroxides of alkali metal elements,ammonium hydroxides, phosphonium hydroxides, and carbonates of alkalimetals.

Examples of the alcohol amines include diethanolamine, triethanolamine,and 2-amino-2-ethyl-1,3-propane diol. Examples of the hydroxide ofalkali metal element include lithium hydroxides, sodium hydroxides, andpotassium hydroxides. Examples of the hydroxide of ammonium includeammonium hydroxides, quaternary ammonium hydroxides, and quaternaryphosphonium hydroxides. Examples of the carbonate of alkali metalinclude lithium carbonates, sodium carbonates, and potassium carbonates.

—Antiseptic-Antifungal Agent—

As the antiseptic-antifungal agent, there may be preferably used, forexample, sodium dehydroacetate, sodium sorbate, sodium2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, anda 1,2-benzoisothiazoline-3-on sodium compound.

—Chelate Reagent—

As the chelate reagent, there may be preferably used, for example,sodium ethylenediamine tetraacetate, sodium nitrilo triacetate, sodiumhydroxyethyl ethylenediamine triacetate, sodium diethylene triaminepentaacetate, and sodium uramil diacetate.

—Anticorrosive Agent—

As the anticorrosive agent, there may be preferably used, for example,acid sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexyl ammoniumnitrite, and 1,2,3-benzotriazole.

—Antioxidant—

As the antioxidant, there may be preferably used, for example,phenol-based antioxidants (including hindered phenol-basedantioxidants), amine-based antioxidants, sulfur-based antioxidants, andphosphorous-based antioxidants.

—Ultraviolet Absorbent—

As the ultraviolet absorbent, there may be preferably used, for example,benzophenone-based ultraviolet absorbents, benzotriazole-basedultraviolet absorbents, salicylate-based ultraviolet absorbents,cyanoacrylate-based ultraviolet absorbents, and nickel complexsalt-based ultraviolet absorbents.

[Ink Production Method]

An ink is produced by dispersing or dissolving a water-dispersiblecolorant, a water-soluble organic solvent, a surfactant, a penetrant andwater, and further, when necessary, other components, in an aqueousmedium, and further, as required, by stirring and mixing thesecomponents. The stirring and mixing can be perfumed by a sand mill, ahomogenizer, a ball mill, a paint shaker, an ultrasonic dispersingmachine or the like, and also performed by a stirrer using stirringblades, a magnetic stirrer, a high-speed dispersing machine or the like.

(Recording Method)

Hereinafter, a recording method according to the present invention willbe further described by way of preferred embodiments. A recording methodaccording to the present embodiment includes making the liquidcomposition according to the present embodiment adhere onto a recordingmedium, and making an ink adhere to the recording medium onto which theliquid composition has been made to adhere. Each of these steps will bedescribed hereinbelow.

—Recording Medium—

As a recording medium for use in the recording method according to thepresent embodiment, regular paper having no coating layer is preferablyused. In particular, the recording medium is preferably regular paperhaving a size degree of 10S or higher and an air permeability of 5S to50S, which is used as copy paper and the like.

<Step of Making Liquid Composition Adhere onto Recording Medium>

The step of making the liquid composition adhere onto a recording mediumis not particularly limited, and a method may be used in which theliquid composition according to the present embodiment is uniformlyapplied to a surface of a recording medium so that the liquidcomposition is attached thereon. Examples of such a method include ablade coating method, a gravure coating method, a gravure offset coatingmethod, a bar coating method, a roll coating method, a knife coatingmethod, an air-knife coating method, a comma coating method, a U-commacoating method, an AKKU coating method, a smoothing coating method, amicro gravure coating method, a reverse roll coating method, coatingmethod using four rollers or five rollers, a dip coating method, acurtain coating method, a slide coating method, and a die coatingmethod.

The wet adhesion amount of the liquid composition (which means anadhesion amount of the liquid composition before a recording medium isdried) to the recording medium in the step of making the liquidcomposition adhere onto a recording medium is preferably 0.1 g/m² to30.0 g/m², and more preferably 0.2 g/m² to 10.0 g/m². When the wetadhesion amount is less than 0.1 g/m², the image quality (image density,color saturation, color bleeding, and feathering) of a recorded mattermay not be improved. When the wet adhesion amount is more than 30.0g/m², the texture of a recorded matter may be impaired and curling mayoccur. Note that, when necessary, a drying step may be provided to drythe recording medium onto which the liquid composition has been made toadhere. In this case, the recording medium may be dried by a rollheater, a drum heater, or hot air.

<Step of Making Ink Adhere onto Recording Medium>

The step of making an ink adhere onto a recording medium in therecording method of the present embodiment is a step in which an ink isapplied to the recording medium onto which the liquid composition of thepresent embodiment has been made to adhere so that the ink is attachedthereon, and thereby an image is recorded on the recording medium. Asthe method of making an ink adhere onto a recording medium, a method ispreferably used in which an impulse (energy) is applied to an ink by apredetermined device to discharge the ink, and thereby the ink is madeadhere onto the recording medium. More specifically, any known inkjetrecording methods can be employed. Examples of such inkjet recordingmethods include an inkjet recording method through scanning with aninkjet recording head, and an inkjet recording method in which an imageis recorded on a certain sheets of recording media by using a line-typeinkjet recording head.

In the step of making the ink adhere to the recording medium, thedriving method of a recording head serving as a unit of discharging anink is not particularly limited, and may be suitably selected inaccordance with the intended use. Examples of the driving method includea method of operating or using a piezoelectric element actuator usingPZT (lead zirconate titanate) or thermal energy; a method of using anon-demand-type recording head using an actuator utilizing anelectrostatic force; and a recording method using a continuous jettingtype-charge controllable recording head. In the method of operating heatenergy, it is said to be difficult to arbitrarily control the jetting ofliquid droplets, and the quality of images recorded is prone tosignificantly vary depending on the type of a recording medium used.This problem is, however, resolved by giving the liquid composition tothe recording medium, and it is possible to obtain a stable and highquality recorded matter irrespective of the type of the recording mediumused. Note that the step of making an ink adhere onto a recording mediumexhibits its effect to a recording medium on which surface has beensufficiently dried as well as to a recording medium on which surface hasnot been dried.

[Recording Apparatus]

A recording apparatus for recording an image by applying the liquidcomposition to a recording medium and applying an ink to the recordingmedium with the liquid composition having adhered to a surface thereofto thereby record an image on the recording medium will be describedwith reference to a specific example illustrated in FIG. 2. Therecording apparatus illustrated in FIG. 2 is a recording apparatus whichrecords an image by scanning the inkjet recording head. In the recordingapparatus illustrated in FIG. 2, a recording medium 6 is sent out by apaper-feed roller 7, and a liquid composition 1 is uniformly and thinlyapplied onto the recording medium 6 by an applying roller 4 and acounter roller 5. The liquid composition 1 is pumped up by a pump-uproller 3 and uniformly applied to the applying roller 4 by a filmthickness controlling roller 2. The recording medium 6 onto which theliquid composition 1 has been applied is then fed to arecording-scanning section where an inkjet recording head 20 is present.Since the length of a paper conveyance route from a start portion (Bportion in FIG. 2) of recording-scanning to an end portion (A portion inFIG. 2) of the operation of applying the liquid composition is designedto be longer than the length of the recording medium in the feedingdirection, application of the liquid composition can be finished at thepoint where the recording medium reaches the start portion ofrecording-scanning. In this case, since application of the liquidcomposition can be carried out before the inkjet recording head 20starts scanning for recording and the recording medium 6 isintermittently conveyed, the liquid composition can be continuouslyapplied to the recording medium 6 in a state where the conveyance speedof the recording medium 6 is constant and uniformly applied theretowithout nonuniformity. Note that the recording apparatus exampleillustrated in FIG. 2 is configured so that the recording medium 6 ontowhich the liquid composition is necessary to be applied is supplied froma lower cassette, and other recording media 17 are supplied from anupper cassette, and thus this is advantageous to provide a longerconveyance route for a recording medium.

FIG. 3 illustrates another example of the recording apparatus of thepresent embodiment. The recording appartus example illustrated in FIG. 3is also an example of a recording apparatus which records by scanning aninkjet head, and this recording apparatus is designed in more compactthan the recording apparatus illustrated in FIG. 2. A recording medium17 is sent out by a paper feeding roller 18, and a liquid composition 1is uniformly applied in a thin thickness to the recording medium 17 byan applying roller 4 and a counter roller 5. The liquid composition 1 ispumped up by a pump-up roller 3 and uniformly applied to the applyingroller 4 by a film thickness control roller 2. The recording medium 17passes a recording-scanning portion where an inkjet recording head 20 ispresent while being applied thereto, and fed until the application ofthe liquid composition 1 to the recording medium 17 is completed. At thetime when the application is completed, the recording medium 17 isreturned back again until a tip portion thereof reaches arecording-scanning start portion. The completion of the application isdetected by proving a known recording medium-detection unit (notillustrated) in the vicinity of the outlet of a liquid compositionapplying unit in the recording apparatus. This detection unit is notnecessarily provided to the recording apparatus, and the recordingapparatus may be systematically configured so that the feed amount ofthe recording medium along the outer peripheral of the conveyance rollercorresponds to the length of the recording medium by preliminarilyinputting information on the length of the recording medium in acontroller and controlling the number of revolutions of the motor.

When double-sided recording is performed, the recording medium 17 ontowhich the liquid composition 1 has been applied is conveyed again to therecording-scanning portion before the liquid composition is dried andsolidified. At this point in time, the recording medium 17 isintermittently conveyed in synchronization with scanning of the inkjetrecording head 20. When the recording medium is made returned to thesame route as that it is sent from first, the rear end of the recordingmedium reversely enters to the liquid composition applying device. Thiscauses failures such as coating nonuniformity, smear, and jamming of therecording medium. When the recording medium is made returned back, thedirection thereof is switched by a recording medium guide 31. That is,when the recording medium 17 is sent in the reverse direction after theliquid composition 1 is applied to the recording medium 17, therecording medium guide 31 is moved to a portion indicated by a dottedline in the figure by a known unit such as a soleide and a motor. Withthis, the recording medium 17 is conveyed to the position of a recordingmedium return guide 34, and thus it is possible to prevent occurrence ofsmear and jamming of the recording medium.

The step of making the liquid composition adhere to the recording mediumis preferably performed at a constant linear speed of 10 mm/s to 1,000mm/s. Therefore, in this recording apparatus example, using sheets of arecording medium, when focused on a certain recording medium sheet,after the process of applying the liquid composition onto the recordingmedium is finished for the certain recording medium sheet, a process ofmaking an ink adhere to a surface thereof and image processing isstarted. In such a recording apparatus, in most cases, the speed ofapplying a liquid composition is inconsistent with the speed ofrecording an image, and thus there is a time lag between a recordingstart portion and a recording end portion of recording sheets of paper,from the time when the liquid composition is applied to the recordingmedium to the time when the image is recorded. Even when the time lag issignificant, in a liquid composition which contains a water-solubleorganic solvent having a boiling point higher than that of water and lowevaporation speed, and in which the water content ratio is adjusted soas to be an amount nearly in equilibrium with the water content in airunder an environment a printer is used, evaporation of water isremarkably suppressed. Thus, a difference in image quality causedbetween a recording start portion and a recording end portion can bereduced to the level where it can be, at least, visually observed.

As clearly understood from the conveyance step of a recording medium inthis recording apparatus, in most cases, there is a need to convey arecording medium to which a liquid composition is applied, through useof a unit for contacting the recording medium, such as a roller, a smallroller, and guide. In this case, when the liquid composition havingadhered to the recording medium is transferred to conveyance members, itmay cause problems, for example, failures occur in the conveyancefunction, and smear is accumulated to cause degradation in quality ofimages. In this case, the occurrence of such problems is reduced byproviding a wavy plate guide in a recording medium, providing aspur-shaped small roller, and/or using a water-repellent material for aroller surface.

To control the operation of a recording apparatus as illustrated inFIGS. 2 and 3, when a recording apparatus receives a printing directionfrom a host machine such as a personal computer, the recording apparatusstarts a head cleaning work and a liquid composition applying worksimultaneously, and at the time all preparations have finished, itstarts recording operation. In this case, the transfer of image data maybe even for one time scanning, even for a plurality of scanning times oreven for one page. The operations of the head cleaning and ink jettingcheck are not necessarily required. In addition, the operations of headcleaning and ink jetting check and the image data processing andtransfer of image data are not necessarily sequentially performed. It ispossible for the recording apparatus to perform these operations inparallel, for example, the operations of coating of the liquidcomposition, head cleaning and ink jetting check and the image dataprocessing and transfer of image data are made to start at the sametime. In this way, by performing these processes in parallel, it ispossible to record an image without substantially decreasing thethrough-put of the recording apparatus even when the recording apparatus(liquid composition applying unit) performs application of the liquidcomposition.

<<Supplemental Description>>

In the recording method of the above-mentioned embodiment, apredetermined ink is made to adhere on a recording medium to therebyrecord an image. That is, the above-mentioned liquid composition is usedas a pre-treatment liquid, which, however, is not limited to theabove-mentioned liquid composition. In this case, an image may berecorded by using the liquid composition as a post-recording treatmentliquid and making the liquid composition adhere onto a recording mediumonto which a predetermined ink has been made to adhere, and an image maybe recorded by using the liquid composition as a recording treatmentliquid and making a predetermined ink and the liquid composition adhereonto a recording medium at the same time.

EXAMPLES

Hereinafter, examples of the present invention will be described,however, the present invention is not limited to the disclosed examples.

<<Production of Ink>> <Production of Resin Coating Pigment Dispersion>(Production of Resin Coating Polymer)

Into a reaction vessel, 20 parts by mass of methylethylketone, 0.03parts by mass of a polymerization chain transfer agent(2-mercaptoethanol), and 10% by mass of each monomer shown in Table 1(represented by parts by mass) were charged, mixed, and then subjectedto a sufficient nitrogen gas substitution to thereby obtain a mixturesolution. Meanwhile, in a dropping funnel, remained 90% by mass of eachof the monomers shown in Table 1 (represented by parts by mass) wascharged, and subsequently 0.27 parts by mass of a polymerization chaintransfer agent (2-mercaptoethanol), 60 parts by mass ofmethylethylketone and 1.2 parts by mass of2,2′-azobis(2,4-dimethylvaleronitrile) were added, mixed, and thensubjected to a sufficient nitrogen gas substitution to thereby obtain amixture solution.

The temperature of the mixture solution in the reaction vessel wasincreased to 75° C. while being stirred under a nitrogen atmosphere, andthe mixture solution in the dropping funnel was gradually added dropwiseto the reaction vessel in 3 hours. After completion of the dropping, theliquid temperature of the resulting mixture solution was maintained at75° C. for 2 hours. Subsequently, a solution, in which 0.3 parts by massof 2,2′-azobis(2,4-dimethylvaleronitrile) were dissolved in 5 parts bymass of methylethylketone, was added to the mixture solution, and thesystem was further aged at 75° C. for 2 hours and at 85° C. for 2 hoursto thereby obtain each solution of [Resin Coating Polymer 1] to [ResinCoating Polymer 4].

Part of the resulting resin coating polymer solution was dried at 105°C. for 2 hours under reduced pressure and isolated by removing thesolvent therefrom. A weight average molecular weight of the resultingsample was measured by gel permeation chromatography, using polystyreneserving as a standard material, 60 mmol/L of phosphoric acid and 50mmol/L of lithium bromide-containing dimethylformamide each serving as asolvent.

TABLE 1 Resin-coating polymer Monomer 1 2 3 4 (A) ethoxy polyethyleneglycol 10 monomethacrylate octoxy polyethylene glycol 10monomethacrylate octoxy polyethylene glycol- 10 polypropylene glycolmonomethacrylate lauroxy polyethylene glycol 10 monomethacrylate (B)methacrylic acid 12 12 14 14 (C) 2-ethylhexyl acrylate 22 22 20 20styrene monomer 46 46 46 46 styrene macromer 10 10 10 10 Weight averagemolecular weight 32,000 41,000 40,000 30,000 Neutralization degree 90 9090 90 Note that details of individual compounds shown in Table 1 are asfollows: * octoxypolyethylene glycol-polyproplylene glycolmonomethacrylate: a monomer to which an oxyethylene group and apropylene group are randomly added (average number of moles added ofpolyethylene glycol: 4, average number of moles added of polypropyleneglycol: 2) * methacrylic acid: produced by Mitsubishi Gas Chemical Co,Inc., product name: GE-110 (MAA) * 2-ethylhexyl methacrylate: producedby Mitsubishi Rayon Co., Ltd., product name: ACRYESTER EH * styrenemonomer: produced by Nippon Steel Chemical Co., Ltd., product name:STYRENEMONOMER * styrene macromer: produced by TOAGOSEI Co., Ltd.,product name: AS-6S (styrene macromer), number average molecular weight:6,000

(Production of Resin Coating Pigment Dispersion)

To 77 parts by mass of a solution in which the concentration of each ofthe resin coating polymers obtained in the above-mentioned productionexample was adjusted to 50% by mass, 90 parts by mass ofmethylethylketone and a predetermined amount of a neutralizing agent (5Nsodium hydroxide aqueous solution) were added to neutralize themethacrylic acid (neutralization degree: 90%). Subsequently 370 parts bymass of ion exchanged water were added thereto and further, 90 parts bymass of a pigment shown in Table 2 were added as a colorant thereto, andthe components were dispersed and mixed, followed by 20 passes ofdispersion treatment by a dispersing machine (MICROFLUIDIZER M-140K, 150MPa). Note that the resin coating pigment dispersions using Carbon BlackNIPEX 150 were subjected to 5 passes of dispersion treatment with thedispersing machine.

To the resulting water dispersion, 100 parts by mass of ion exchangedwater were added, stirred, and the methylethylketone was removedtherefrom at 60° C. under reduced pressure. Further, part of water wasremoved from the water dispersion, and then filtered through aneedle-less syringe (capacity: 25 mL) [manufactured by TERUMOCorporation] to which a 5 μm-filter [acetyl cellulose film, outerdiameter: 2.5 cm, produced by Fujifilm Corporation] was attached toremove coarse particles therefrom, thereby obtaining aqueous dispersionsof Production Examples B-1 to B-4 (solid fraction: 25% by mass).

TABLE 2 Resin Production coating Example polymer Pigment B-1 1 CarbonBlack NIPEX150 (produced by Degussa HÜLS AG) B-2 2 C.I. Pigment Yellow74 (produced by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) B-3 3C.I. Pigment Red 122 (produced by Dainichiseika Color & Chemicals Mfg.Co., Ltd.) B-4 4 C.I. Pigment Blue 15:3 (produced by Dainichiseika Color& Chemicals Mfg. Co., Ltd.)

<Production of Pigment-Surfactant Dispersion> Production Example C-1Production of Black Pigment-Surfactant Dispersion

-   Carbon Black (NIPEX150, produced by Degussa HÜLS AG) . . . 15.0    parts by mass-   polyoxyethylene styrene phenylether sulfonate ammonium (anionic    surfactant, produced by DAI-ICHI KOGYO SEIYAKU CO., LTD., HITENOL    NF-17) . . . 6.0 parts by mass-   ion exchanged water . . . 79.0 parts by mass

First, the surfactant listed above was dissolved in ion exchanged water,the carbon black was mixed therewith, and the sufficiently wetted. Then,the system was subjected to 5 passes of dispersion treatment withMICROFLUIDIZER M-140K, 150 MPa (manufactured by Mizuho Kogyo K.K.) toobtain a primary pigment dispersion. Next, to the primary pigmentdispersion, 2.13 parts by mass of a water-soluble polyurethane resin(TAKELAC W-5661, produced by Mitsui Chemicals, Inc., effectivecomponent: 35.2% by mass, acid value: 40 mgKOH/g, molecular weight:18,000) were added as a water-soluble polymer compound aqueous solution,and sufficiently stirred to thereby obtain a black pigment-surfactantdispersion. An average particle diameter (D₅₀) of the pigment dispersionin the resulting black pigment-surfactant dispersion was measured usinga particle size distribution measurement device (manufactured by NIKKISOCo., Ltd., NANOTRACK UPA-EX150) and found to be 132 nm.

Production Example C-2 Production of Yellow Pigment-SurfactantDispersion

-   monoazo yellow pigment (C.I. Pigment Yellow 74, produced by    Dainichiseika Color & Chemicals Mfg. Co., Ltd.) . . . 20.0 parts by    mass-   polyoxyethylene-β-naphthylether (nonionic surfactant, produced by    TAKEMOTO OIL & FAT Co., RT-100, HLB value=18.5) . . . 7.0 parts by    mass-   ion exchanged water . . . 73.0 parts by mass

First, the surfactant listed above was dissolved in ion exchanged water,the pigment listed above was mixed therewith, and the sufficientlywetted. Then, the system was dispersed at 2,000 rpm for 2 hours by awet-process dispersing machine (DYNOMILL KDL A Model, manufactured byWAB Co.) which was filled with zirconia beads having a diameter of 0.5mm, to obtain a primary pigment dispersion. Next, to the primary pigmentdispersion, 2.84 parts by mass of a water-soluble polyurethane resin(TAKELAC W-5661, produced by Mitsui Chemicals, Inc., effectivecomponent: 35.2% by mass, acid value: 40 mgKOH/g, molecular weight:18,000) were added as a water-soluble polymer compound aqueous solution,and sufficiently stirred to thereby obtain a yellow pigment-surfactantdispersion. An average particle diameter (D₅₀) of the pigment dispersionin the resulting yellow pigment-surfactant dispersion was measured usinga particle size distribution measurement device (manufactured by NIKKISOCo., Ltd., NANOTRACK UPA-EX150) and found to be 76 nm.

Production Example C-3 Magenta Pigment-Surfactant Dispersion

-   quinacridone pigment (C.I. Pigment Red 122, produced by    Dainichiseika Color & Chemicals Mfg. Co., Ltd.) . . . 20.0 parts by    mass-   polyoxyethylene-β-naphthylether (nonionic surfactant, produced by    TAKEMOTO OIL & FAT Co., RT-100, HLB value=18.5) . . . 7.0 parts by    mass-   ion exchanged water . . . 73.0 parts by mass

First, the surfactant listed above was dissolved in ion exchanged water,the pigment listed above was mixed therewith, and the sufficientlywetted. Then, the system was dispersed at 2,000 rpm for 2 hours by awet-process dispersing machine (DYNOMILL KDL A Model, manufactured byWAB Co.) which was filled with zirconia beads having a diameter of 0.5mm, to obtain a primary pigment dispersion. Next, to the primary pigmentdispersion, 2.84 parts by mass of a water-soluble polyurethane resin(TAKELAC W-5661, produced by Mitsui Chemicals, Inc., effectivecomponent: 35.2% by mass, acid value: 40 mgKOH/g, molecular weight:18,000) were added as a water-soluble polymer compound aqueous solution,and sufficiently stirred to thereby obtain a magenta pigment-surfactantdispersion. An average particle diameter (D₅₀) of the pigment dispersionin the resulting magenta pigment-surfactant dispersion was measuredusing a particle size distribution measurement device (manufactured byNIKKISO Co., Ltd., NANOTRACK UPA-EX150) and found to be 86 nm.

Production Example C-4 Cyan Pigment-Surfactant Dispersion

-   phthalocyanine pigment (C.I. Pigment Blue 15:3, produced by    Dainichiseika Color & Chemicals Mfg. Co., Ltd.) . . . 20.0 parts by    mass-   polyoxyethylene-β-naphthylether (nonionic surfactant, produced by    TAKEMOTO OIL & FAT Co., RT-100, HLB value=18.5) . . . 7.0 parts by    mass-   ion exchanged water . . . 73.0 parts by mass

First, the surfactant listed above was dissolved in ion exchanged water,the pigment listed above was mixed therewith, and the sufficientlywetted. Then, the system was dispersed at 2,000 rpm for 2 hours by awet-process dispersing machine (DYNOMILL KDL A Model, manufactured byWAB Co.) which was filled with zirconia beads having a diameter of 0.5mm, to obtain a primary pigment dispersion. Next, to the primary pigmentdispersion, 2.84 parts by mass of a water-soluble polyurethane resin(TAKELAC W-5661, produced by Mitsui Chemicals, Inc., effectivecomponent: 35.2% by mass, acid value: 40 mgKOH/g, molecular weight:18,000) were added as a water-soluble polymer compound aqueous solution,and sufficiently stirred to thereby obtain a cyan pigment-surfactantdispersion. An average particle diameter (D₅₀) of the pigment dispersionin the resulting cyan pigment-surfactant dispersion was measured using aparticle size distribution measurement device (manufactured by NIKKISOCo., Ltd., NANOTRACK UPA-EX150) and found to be 106 nm.

<Preparation of Ink>

Each inkjet ink was produced according to the following procedure.First, a water-soluble organic solvent, a penetrant, a surfactant, anantifungal agent and water shown in Tables 3-1A, 3-1B, 3-2A and 3-2Bwere mixed and stirred for 1 hour so as to be uniformly mixed. Inaddition, depending on the mixture liquid, a water-dispersible resin wasadded, and stirred for 1 hour. Further, the pigment dispersion, ananti-foaming agent and a pH adjustor were added to the mixture liquidand stirred for 1 hour. This dispersion liquid was filtered underpressure through a polyvinylidene fluoride-membrane filter having anaverage pore diameter of 5.0 μm to remove coarse particles and wastetherefrom, thereby producing Inks (K1 to K4, Y1 to Y4, M1 to M4, and C1to C4).

TABLE 3-1A Ink Component (% by mass) K1 Y1 M1 C1 K2 Y2 M2 C2 PigmentProduction Ex. B-1 45.71 dispersion Production Ex. B-2 28.57 ProductionEx. B-3 45.71 Production Ex. B-4 28.57 Production Ex. C-1 53.33Production Ex. C-2 25.00 Production Ex. C-3 40.00 Production Ex. C-425.00 Water-dispersible acryl-silicone 2.50 3.75 2.50 3.75 resin resinemulsion Water-soluble 1,3-butanediol 13.00 18.00 19.00 26.00 22.0 25.00organic solvent 3-methyl-1,3-butanediol 16.00 15.00 glycerin 16.00 26.0018.00 19.00 15.00 13.00 11.00 12.50

TABLE 3-1B Ink Component (% by mass) K1 Y1 M1 C1 K2 Y2 M2 C2 Penetrant2-ethyl-1,3-hexanediol 2.00 2.00 2.00 2.002,2,4-trimethyl-1,3-pentanediol 2.00 2.00 2.00 2.00 Anti-foaming2,4,7,9-tetramethyldecane-4,7-diol 0.40 0.25 0.25 0.25 0.25 agent2,5,8,11-tetramethyldodecane-5,8-diol 0.40 0.40 0.40 KM-72FFluorine-based Compound represented by (F-1)-e) 0.10 0.10 0.10 0.10surfactant Compound represented by (F-2) 0.05 0.05 0.05 0.05 Compoundrepresented by (F-3-1) Compound represented by (F-4-1) Antifungal PROXELGXL 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 agent pH adjuster2-amino-2-ethyl-1,3-propanediol 0.30 0.40 0.40 0.40 0.60 0.30 0.30 0.30Pure water balance balance balance balance balance balance balancebalance Total (% by mass) 100 100 100 100 100 100 100 100

TABLE 3-2A Ink Component (% by mass) K3 Y3 M3 C3 K4 Y4 M4 C4 PigmentProduction Ex. B-1 22.86 dispersion Production Ex. B-2 5.71 ProductionEx. B-3 9.14 Production Ex. B-4 5.71 Production Ex. C-1 26.67 ProductionEx. C-2 20.00 Production Ex. C-3 32.00 20.00 Production Ex. C-4 Blackself-dispersible pigment dispersion 53.33 (CAB-O-JET300) Yellowself-dispersible pigment dispersion 45.45 (CAB-O-JET270) Magentaself-dispersible pigment dispersion 54.55 (CAB-O-JET260) Cyanself-dispersible pigment dispersion 45.45 (CAB-O-JET250) Water-soluble1,3-butanediol 27.50 26.00 27.60 25.00 22.00 24.00 organic solvent3-methyl-1,3-butanediol 16.50 15.50 glycerin 16.50 13.75 13.00 13.8015.50 12.50 11.00 12.00

TABLE 3-2B Ink Component (% by mass) K3 Y3 M3 C3 K4 Y4 M4 C4 Penetrant2-ethyl-1,3-hexanediol 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.002,2,4-trimethyl-1,3-pentanediol Anti-foaming2,4,7,9-tetramethyldecane-4,7-diol 0.25 0.25 0.25 0.25 agent2,5,8,11-tetramethyldodecane-5,8-diol KM-72F 0.10 0.10 0.10 0.10Fluorine-based Compound represented by (F-1)-e) 0.05 0.05 0.05 0.05surfactant Compound represented by (F-2) Compound represented by (F-3-1)0.05 Compound represented by (F-4-1) 0.05 0.05 0.05 Antifungal PROXELGXL 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 agent pH adjuster2-amino-2-ethyl-1,3-propanediol 0.60 0.30 0.30 0.30 1.20 0.30 0.30 0.30Pure water balance balance balance balance balance balance balancebalance Total (% by mass) 100 100 100 100 100 100 100 100 Abbreviationsin Tables 3-1A, 3-1B, 3-2A and 3-2B represent the following meaning: *CAB-O-JET 260: produced by CABOT Co., pigment solid fraction: 11% bymass, self-dispersible magenta pigment * CAB-O-JET 250: produced byCABOT Co., pigment solid fraction: 11% by mass, self-dispersible cyanpigment * CAB-O-JET 270: produced by CABOT Co., pigment solid fraction:11% by mass, self-dispersible yellow pigment * CAB-O-JET 300: producedby CABOT Co., pigment solid fraction: 15% by mass, self-dispersibleblack pigment * acryl-silicone resin emulsion: produced by Showa HighPolymer Co., Ltd., POLYZOLE ROY6312, solid fraction: 40% by mass,average particle diameter: 171 nm, minimum film-forming temperature(MFT): 20° C. * PROXEL GXL: PROXEL GXL: antifungal agent mainlycontaining 1,2-benzisothiazolin-3-one (produced by Avicia Co.,component: 20% by mass, containing dipropylene glycol) * KM-72F:self-emulsified type silicone anti-foaming agent (produced by Shin-Etsusilicone Corp., component: 100% by mass)

Next, each of the inks produced as above was evaluated according to thefollowing evaluation methods. The evaluation results are shown in Table4.

Average particle diameter (D₅₀): measured at 25° C. by a particle sizedistribution measurement device (NANOTRACK UPA-EX150, manufactured byNIKKISO Co., Ltd.)

Viscosity: measured at 25° C. by a viscometer (RE-550L, manufactured byTOKI SANGYO Co., Ltd.)

Surface tension: measured at 25° C. by an automatic surface tensionmeter (CBVP-Z, manufactured by Kyowa Interface Science Co., LTD.)

TABLE 4 Physical Properties of Ink Average particle Surface diameter D₅₀Viscosity tension (nm) (mPa · s) (mN/m) K1 79.5 8.10 21.5 Y1 95.6 7.9821.0 M1 95.9 8.03 21.3 C1 81.3 8.00 20.9 K2 133.3 8.08 22.4 Y2 82.4 8.0021.7 M2 92.6 8.09 21.6 C2 108.6 8.14 21.6 K3 110.4 6.25 24.9 Y3 92.86.12 25.1 M3 135.2 6.41 25.0 C3 130.1 6.26 25.2 K4 124.1 7.92 24.5 Y484.1 7.85 23.5 M4 94.5 7.88 24.7 C4 98.8 7.89 24.7

<<Production of Liquid Composition>> <Production of Cationic Polymer>Production Example A-1 Copolymer of N,N-dimethylallylamine Hydrochlorideand N-methyldiallylamine Hydrochloride (Charged Molar Ratio: 0.7:0.3)

Into a 1 L-separable flask reaction vessel equipped with a stirrer, athermometer and a reflux condenser, a 71.66% by massN,N-dimethylallylamine hydrochloride aqueous solution (237.58 g (1.4mol)) and a 60.17% by mass N-methyldiallylamine hydrochloride aqueoussolution (147.23 g (0.6 mol)) were added to obtain an aqueous solutionof having a monomer concentration of 67.27% by mass. This aqueoussolution was heated to 60°. After the temperature of the aqueoussolution was constant, ammonium persulfate (4.56 g (1.0 mol % relativeto monomer)) was added as a radical polymerization initiator to theaqueous solution to initiate polymerization. Also, 2 hours later, and 4hours later of the initiation of polymerization, ammonium persulfate(4.56 g (1.0 mol % relative to monomer)) was added to the reactionsystem for each time. Furthermore, 23 hours later, 24 hours later, 25hours later, 26 hours later, 27 hours later and 28 hours later of theinitiation of polymerization, ammonium persulfate (9.13 g (2.0 mol %relative to monomer)) was added to the reaction system for each time.Thereafter, the polymerization reaction was further continued for 3hours to thereby obtain a brown solution (Production Example A-1) of acopolymer of N,N-dimethylallylamine hydrochloride andN-methyldiallylamine hydrochloride (charged molar ratio: 0.7:0.3). Aweight average molecular weight of the copolymer determined by GPC (GelPermeation Chromatography) was 1,800.

Production Example A-2 Copolymer of N,N-dimethylallylamine Hydrochlorideand N-methyldiallylamine Hydrochloride (Charged Molar Ratio: 0.9:0.1)

Into a reaction vessel (the same type as used in Production ExampleA-1), a 61.54% by mass N,N-dimethylallylamine hydrochloride aqueoussolution (533.56 g (2.7 mol)) and a 60.17% by mass N-methyldiallylaminehydrochloride aqueous solution (73.62 g (0.3 mol)) were added to obtainan aqueous solution of having a monomer concentration of 61.37% by mass.This aqueous solution was heated to 60°. After the temperature of theaqueous solution was constant, ammonium persulfate (6.85 g (1.0 mol %relative to monomer)) was added as a radical polymerization initiator tothe aqueous solution to initiate polymerization. Also, 2 hours later,and 4 hours later of the initiation of polymerization, ammoniumpersulfate (6.85 g (1.0 mol % relative to monomer)) was added to thereaction system for each time. Furthermore, 23 hours later, 24 hourslater, 25 hours later, 26 hours later, 27 hours later, 47 hours laterand 48 hours later of the initiation of polymerization, ammoniumpersulfate (13.69 g (2.0 mol % relative to monomer)) was added to thereaction system for each time. Thereafter, the polymerization reactionwas further continued for 2 hours to thereby obtain a brown solution(Production Example A-2) of a copolymer of N,N-dimethylallylaminehydrochloride and N-methyldiallylamine hydrochloride (charged molarratio: 0.9:0.1). A weight average molecular weight of the copolymerdetermined by GPC (Gel Permeation Chromatography) was 700.

Production Example A-3 Copolymer of Monoallylamine Hydrochloride andN,N-dimethylallylamine Hydrochloride (Charged Molar Ratio: 0.5:0.5)

Into a 300 ml-three-necked flask equipped with a stirrer, a thermometer,and a reflux condenser, a 72.11% by mass monoallylamine hydrochlorideaqueous solution (64.87 g (0.50 mol)) and a 60.21% by massN,N-dimethylallylamine hydrochloride aqueous solution (100.99 g (0.50mol) were charged, and water (13.45 g) was added to obtain an aqueoussolution having a monomer concentration of 60% by mass. This aqueoussolution was heated to 60° C. After the temperature of the aqueoussolution was constant, 2,2-azobis(2-amidinopropane)dihydrochloride (8.68g (3.2 mol % relative to monomer)) was added as a radical polymerizationinitiator to the aqueous solution to initiate polymerization. Also, 24hours later, 48 hours later and 72 hours later of the initiation ofpolymerization, 2,2-azobis(2-amidinopropane)dihydrochloride (8.68 g) wasadded to the reaction system for each time. Thereafter, thepolymerization reaction was further continued for 24 hours to obtain alight yellow reaction solution. Thereafter, the resulting light yellowreaction solution was poured into 3 litters of acetone-isopropanolmixture solvent (mass ratio: 1:1) to reprecipitate the copolymer,filtered through a glass filter, and then sufficiently washed, followedby vacuum drying at 60° C. for 48 hours to thereby obtain a brownsolution (Production Example A-3) of a copolymer of monoallylaminehydrochloride and N,N-dimethylallylamine hydrochloride (charged molarratio: 0.5:0.5). A weight average molecular weight of the copolymerdetermined by GPC (Gel Permeation Chromatography) was 800.

Production Example A-4 Diallyldimethylamine Hydrochloride-Sulfur DioxideCopolymer

Into a 300 ml-four-necked flask equipped with a stirrer, a thermometer,and a reflux condenser, a 1 mol/L diallyldimethylaminehydrochloride/diemthylsulfoxide (100 ml) and a 1 mol/L sulfurdioxide/diemthylsulfoxide solution (100 ml) were added and mixed, andazobis-isobutylonitrile (0.82 g) was added as a polymerization initiatorto the mixture, followed by polymerizing at 40° C. for 24 hours. Thereaction solution was added dropwise to methanol to precipitate thecopolymer, filtered through a glass filter, followed by drying underreduced pressure, thereby obtaining 18 g of a copolymerized polymer(Production Example A-4). A weight average molecular weight of thecopolymer determined by GPC (Gel Permeation Chromatography)(polyethylene glycol used as a standard) was about 3,000. The repeatingunit of this polymer is represented by Formula (6) below.

Production Example A-5 Diallyldimethyl Ammonium Chloride-AcrylamideCopolymer

Into a 500 ml-four-necked flask equipped with a stirrer, a thermometer,and a reflux condenser, a 60% by mass diallyldimethyl ammonium chlorideaqueous solution (134.7 g (0.5 mol)) and distilled water (176 g) werecharged, and the pH of the mixture was adjusted with chloride to 3 to 4.Next, acrylamine (18.3 g (0.25 mol) and sodium hypophosphite (3.9 g)were added thereto, and stirred at 50° C. to be dissolved. Next, theinternal temperature of the system was increased to 60° C., and a 28.5%by mass ammonium persulfate aqueous solution (1.7 g) was added thereto.Four hours later, the ammonium persulfate aqueous solution (3.5 g) wasfurther added while the internal temperature of the system beingmaintained at 60° C. to 65° C. Thereafter, the reaction system wasreacted at 60° C. for 20 hours to thereby obtain a diallyldimethylammonium chloride-acrylamide copolymer (Production Example A-5). Aweight average molecular weight of the copolymer was determined by GPC(Gel Permeation Chromatography) and found to be 3,000.

<Production of Liquid Composition>

Each liquid composition was produced according to the followingprocedure. First, materials shown in Tables 5A and 5B were mixed, andstirred so as to be uniformly mixed, thereby obtaining a pretreatmentliquid. This pretreatment liquid was filtered under pressure through apolyvinylidene fluoride membrane having an average pore diameter of 5.0μm to remove coarse particles and waste to thereby produce LiquidCompositions 1 to 11. Physical properties of Liquid Compositions 1 to 11are shown in Table 6. The measurement of a surface tension of the liquidcompositions was performed in a similar manner to that of the surfacetension of ink. As for coating properties of each liquid composition,the liquid composition was applied to a recording medium by a rollcoater, and evaluated by visual observation based on the followingcriteria.

[Evaluation Criteria]

A: No problem (no foaming and no uneven coating observed)

B: Slightly problematic (foaming and uneven coating slightly observed)

TABLE 5A Liquid Composition Component (% by mass) 1 2 3 4 5 Organic acidlactic acid ammonium 13.33 6.67 6.67 ammonium (content: 75%) lactic acidammonium 10.31 (content: 97%) tartaric acid 10.20 (content: 98%)Inorganic calcium nitrate metal salt compound Cationic A-1 20.00 polymerA-2 A-3 A-4 20.00 A-5 SHAROL DC-902P Water-soluble3-methyl-1,3-butanediol 10.00 10.00 10.00 10.00 10.00 organic solventglycerin 20.00 20.00 20.00 20.00 20.00 Penetrant 2-ethyl-1,3-hexanediol1.00 1.00 1.00 1.00 1.00 Anti-foaming 2,4,7,9-tetramethyldecane- 0.100.10 0.10 0.10 agent 4,7-diol 2,5,8,11-tetramethyldodecane- 0.105,8-diol Fluorine- Compound represented by 0.20 0.20 0.20 based (F-1)-e)surfactant Compound represented by 0.20 0.30 (F-2) Compound representedby (F-3-1) Compound represented by (F-4-1) Surfactant SOFTANOL EP7025Anti-fungal PROXEL GXL 0.05 0.05 0.05 0.05 0.05 agent Anti-corrosive1,2,3-benzotriazole 0.05 0.05 0.05 0.05 0.05 agent Pure water *1 *1 *1*1 *1 Total (% by mass) 100 100 100 100 100 *1: balance

TABLE 5B Liquid composition Component (% by mass) 6 7 8 9 10 11 Organicacid lactic acid ammonium 6.67 6.67 13.33 6.67 6.67 ammonium (content:75%) lactic acid ammonium (content: 97%) tartaric acid (content: 98%)Inorganic calcium nitrate 20.41 metal salt compound Cationic A-1 20.00polymer A-2 6.61 A-3 A-4 A-5 20.00 SHAROL DC-902P 19.23 19.23 19.23Water-soluble 3-methyl-1,3-butanediol 20.00 15.00 15.00 15.00 15.0010.00 organic solvent glycerin 15.00 20.00 20.00 20.00 15.00 20.00Penetrant 2-ethyl-1,3-hexanediol 1.00 1.00 1.00 1.00 1.00 Anti-foaming2,4,7,9-tetramethyldecane- 0.10 0.10 agent 4,7-diol2,5,8,11-tetramethyldodecane- 0.10 5,8-diol Fluorine- Compoundrepresented by 0.20 0.20 0.20 based (F-1)-e) surfactant Compoundrepresented by 0.20 (F-2) Compound represented by (F-3-1) Compoundrepresented by (F-4-1) Surfactant SOFTANOL EP7025 0.50 0.50 Anti-fungalPROXEL GXL 0.05 0.05 0.05 0.05 0.05 0.05 agent Anti-corrosive1,2,3-benzotriazole 0.05 0.05 0.05 0.05 0.05 0.05 agent Pure water *1 *1*1 *1 *1 *1 Total (% by mass) 100 100 100 100 100 100 *1: balanceAbbreviations in Tables 5A and 5B represent the following meaning: *lactic acid ammonium: produced by Kanto Chemical Co., Inc., purity:99.5% or more * lactic acid ammonium: produced by Kanto Chemical Co.,Inc., purity: 99.5% or more * tartaric acid ammonium: produced by KantoChemical Co., Inc., purity: 99.5% or more * SHAROL DC-902P: polydimethyldiallyl ammonium chloride (produced by DAI-ICHI KOGYO SEIYAKU CO., LTD.,effective component: 52% by mass, average molecular weight: 9,000) *ZONYL FS-300: polyoxyethylene perfluoroalkylether (produced by Dupont,effective component: 40% by mass) * KF-643: polyether-modifiedsilicone-based surfactant (produced by Shin-Etsu Chemical Co., Ltd.,effective component: 100% by mass) * SOFTANOL EP-7025: polyoxyalkylenealkylether (produced by Nippon Shokubai Co., Ltd., component: 100% bymass) * FTERGENT 251: branched perfluoroalkenyl group-containingfluorine-based surfactant (produced by Neos Co., Ltd., effectivecomponent: 100% by mass) * PROXEL GXL: antifungal agent mainlycontaining 1,2-benzisothiazolin-3-one (produced by Avicia Co.,component: 20% by mass, containing dipropylene glycol)

TABLE 6 Surface Liquid tension Coating composition pH (mN/m) properties1 6.17 20.6 A 2 5.92 20.8 A 3 6.57 21.1 A 4 6.41 20.9 A 5 6.26 20.7 A 66.14 21.6 A 7 6.19 20.3 A 8 6.29 20.9 A 9 6.50 30.8 B 10 6.82 31.3 B 115.95 21.0 B<<Step of Making Liquid Composition Adhere onto Recording Medium>>

In each Examples and Comparative Examples excluding Comparative Examples1 to 4, a liquid composition described in Table 7 was made to adhereonto a recording medium (RECYCLE PPC: produced by Daio Paper Corporation(recycled paper), basis weight: 66.5 g/m², recycled waste pulp-mixedrate: 70% or more, sizing degree: 17 sec, air permeability: 35 sec). Inthis case, each of Liquid Compositions 1 to 10 was applied, in anadhesion amount of 0.8 g/m², to the recording medium by a roll coatingmethod, using the recording apparatus illustrated in FIG. 2 or FIG. 3,and then naturally dried.

<<Step of Making Ink Adhere onto Recording Medium>>

In the step of making an ink adhere onto a recording medium, concerningeach Examples and Comparative Examples, using an inkjet recordingapparatus (IPSIO GX5000, manufactured by Ricoh Company Ltd.) to which anink set described in Table 7 had been mounted, an image was recorded byapplying an ink onto the recording medium shown in Table 7 which hadbeen produced by the step of making a liquid composition onto therecording medium, and thereby an image was recorded. ConcerningComparative Examples 1 to 4, each ink was applied to a recording medium(RECYCLE PPC) on which surface no liquid composition was applied, andthereby an image was recorded. Since images recorded differ for everyevaluation item, and thus the details of the images used will bedescribed in the paragraph “Recorded Matter”. Note that at the time ofapplying an ink to the recording medium, the driving voltage of apiezoelectric element was varied so that the discharge amounts of theindividual inks were equal to each other, under the environment of 23°C.±0.5° C. and 50% RH±5% RH. In addition, the printing mode when eachink was applied was set to “Regular Paper/Clear Mode, Color Matching:OFF”.

TABLE 7 Liquid composition Ink set Ex. 1 1 1 Ex. 2 2 2 Ex. 3 2 3 Ex. 4 24 Ex. 5 5 1 Ex. 6 6 1 Ex. 7 7 4 Ex. 8 8 4 Ex. 9 9 4 Ex. 10 7 1 Ex. 11 72 Ex. 12 7 3 Ex. 13 11 2 Comp. Ex. 1 1 Comp. Ex. 2 2 Comp. Ex. 3 3 Comp.Ex. 4 4 Comp. Ex. 5 10 4 Comp. Ex. 6 3 1 Comp. Ex. 7 4 1 Note that, eachof the ink sets shown in Table 7 is composed of the inks describedbelow. * Ink Set 1: Ink M1, Ink C1, Ink Y1, Ink K1 * Ink Set 2: Ink M2,Ink C2, Ink Y2, Ink K2 * Ink Set 3: Ink M3, Ink C3, Ink Y3, Ink K3 * InkSet 4: Ink M4, Ink C4, Ink Y4, Ink K4

<<Evaluation of Recorded Matter>>

Recording matters obtained using Examples and Comparative Examples wereevaluated for the following items.

<Density>

Concerning a recorded matter which was recorded by means of MICROSOFT(registered) Word 2000, in which a character “▪” was recorded (fontsize: 64 point), the density of the “▪” portion on a recorded surfacewas measured by an X-Rite 938, and evaluated based on the followingcriteria.

[Evaluation Criteria]

-   -   A: Black: 1.45 or higher,        -   Yellow: 0.90 or higher,        -   Magenta: 1.15 or higher,        -   Cyan: 1.20 or higher    -   B: Black: 1.35 or higher but lower than 1.45,        -   Yellow: 0.85 or higher but lower than 0.90,        -   Magenta: 1.05 or higher but lower than 1.15,        -   Cyan: 1.10 or higher but lower than 1.20    -   C: Black: lower than 1.35,        -   Yellow: lower than 0.85,        -   Magenta: lower than 1.05,        -   Cyan: lower than 1.10

<Strikethrough>

A recorded matter which was recorded by means of MICROSOFT (registered)Word 2000, in which a character “▪”was recorded (font size: 64 point),was measured for colorimetry at its rear surface to the recorded surfacewhere “▪”was recorded, by an X-Rite 938. A density obtained bysubtracting the density of the background of the recording medium wasregarded as “strikethrough density”. The measured strikethrough densitywas graded based on the following criteria.

[Evaluation Criteria]

-   -   A: Black: lower than 0.09,        -   Yellow: lower than 0.08,        -   Magenta: lower than 0.09,        -   Cyan: lower than 0.09,    -   B: Black: 0.09 or higher but lower than 0.10,        -   Yellow: 0.08 or higher but lower than 0.09,        -   Magenta: 0.09 or higher but lower than 0.10,        -   Cyan: 0.09 or higher but lower than 0.10,    -   C: Black: 0.10 or higher,        -   Yellow: 0.09 or higher,        -   Magenta: 0.10 or higher,        -   Cyan: 0.10 or higher

<Color Bleeding>

Concerning a recorded matter on which surface 0.5-mm line images foreach color of magenta, cyan and black were recorded on a yellow solidimage, occurrence of bleeding at color boundary where different colorinks were recorded was visually observed. Similarly to the above, arecorded matter on which surface 0.5-mm line images for each color ofmagenta, yellow and black were recorded on a cyan solid image, and arecorded matter on which surface 0.5-mm line images for each color ofcyan, yellow and black were recorded on a magenta solid image were alsovisually observed for presence or absence of bleeding at color boundary.

[Evaluation Criteria]

-   -   A: No problem at all    -   B: Slightly occurred but no problem    -   C: Occurred    -   D: Problematic

<Feathering>

Concerning a recorded matter which was recorded by means of MICROSOFT(registered) Word 2000, in which a black character was recorded (fontsize: 6 point), occurrence of feathering at the following characterportion was visually observed.

[Evaluation Criteria]

-   -   A: No problem at all    -   B: Slightly occurred but no problem    -   C: Occurred in small percentage, problematic    -   D: Occurred, problematic

<White Spot>

Concerning a recorded matter which was recorded by means of MICROSOFT(registered) Word 2000, in which a character “▪”was recorded in eachcolor of yellow, magenta, cyan, and black (font size: 64 point), the “▪”portion was visually observed, and presence or absence of white spots(void portions in the character “▪”) was evaluated.

[Evaluation Criteria]

-   -   A: No problem at all    -   B: Slightly observed, but no problem    -   C: Observed, but within an allowable range    -   D: Problematic

<Fixability>

A recorded matter which was recorded by means of MICROSOFT (registered)Word 2000, in which a monochrome black solid image (3 cm×3 cm) wasrecorded, was dried at 23° C.±1° C. and 50% RH±10% RH for 24 hours.Subsequently, JIS L 0803 Cotton No. 3 that had been attached to a CM-1model clockmeter with a double-sided tape was moved to-and-fro on therecorded matter 5 times so that it was applied to the monochrome blacksolid image in the recorded matter, and then the density of the cottoncloth to which the ink had been attached was measured by an X-Rite 938.The density of the background color of the cotton cloth was subtractedfrom the measured density value, and the result was regarded as adensity of smeared portions. The density of the smeared portions wasgraded based on the following evaluation criteria.

[Evaluation Criteria]

-   -   A: lower than 0.15    -   B: 0.15 or higher but lower than 0.25    -   C: 0.25 or higher

<Drying Properties>

A recorded matter which was recorded by means of MICROSOFT (registered)Word 2000, in which a monochrome black solid image (3 cm×3 cm) wasproduced. Subsequently, immediately after the recording of the image (10minutes later), JIS L 0803 Cotton No. 3 that had been attached to a CM-1model clockmeter with a double-sided tape was moved to-and-fro on therecorded matter 5 times so that it was applied to the monochrome blacksolid image in the recorded matter, and then the density of the cottoncloth to which the ink had been attached was measured by an X-Rite 938.The density of the background color of the cotton cloth was subtractedfrom the measured density value, and the result was regarded as adensity of smeared portions. The density of the smeared portions wasgraded based on the following evaluation criteria. Note that theevaluation was performed under the environment of 23° C.±1° C. and 50%RH±10% RH.

[Evaluation Criteria]

-   -   A: lower than 0.2    -   B: 0.2 or higher but lower than 0.3    -   C: 0.3 or higher

The evaluation results are shown in Table 8. The inks were evaluated foreach color based on the evaluation criteria described above. Note thatas for the results of image quality of recorded matters, the most commonevaluation grade was described as the result. When the number ofevaluation grades was equal, the better grade was described as theresult.

TABLE 8 Abra- Color sion Drying Image Strike- Feath- bleed- White resis-prop- density through ering ing spot tance erties Ex. 1 B A A A B A AEx. 2 A B B A A A A Ex. 3 A A A A A A A Ex. 4 A B A A A A A Ex. 5 A A AA A B B Ex. 6 A A A A A B B Ex. 7 A A A A A A A Ex. 8 A A A A A A A Ex.9 A A A A A B B Ex. 10 A A A A A A A Ex. 11 A B B A A A A Ex. 12 A A B AA A A Ex. 13 A B B A A A A Comp. C C B B B B B Ex. 1 Comp. C C C D C A AEx. 2 Comp. C C C D C A A Ex. 3 Comp. C C C D C A A Ex. 4 Comp. A A A AA C C Ex. 5 Comp. C C C B C A A Ex. 6 Comp. C C C B C A A Ex. 7

REFERENCE SIGNS LIST

-   1 liquid composition-   2 film thickness control roller-   3 pump-up roller-   4 applying roller-   5 counter roller-   6 recording medium-   7 paper feeding roller-   8 paper feeding tray-   10 paper feed roller-   11 recording medium feed roller-   12 recording medium feed roller-   13 recording medium feed roller-   14 recording medium feed roller-   15 recording medium feed roller-   16 recording medium feed roller-   17 recording medium-   18 paper feeding roller-   20 recording head-   21 ink cartridge-   22 carriage shaft-   23 carriage-   31 recording medium guide-   32 recording medium feed roller-   33 recording medium feed roller-   34 recording medium send-back roller-   35 paper feed guide-   101 recording medium-   102 liquid composition-attached portion-   103 ink-attached portion-   104 colorant

1. A liquid composition comprising: an organic acid ammonium salt ofFormula (1), and water,

where R₁ is a hydroxyl group, a methyl group or a hydrogen atom; and R₂is a hydroxyl group or a methyl group wherein the liquid composition issuitable for agglutinating particles having a negative charge which aredispersed in a dispersion liquid.
 2. The liquid composition of claim 1,wherein the organic acid ammonium salt is ammonium lactate.
 3. Theliquid composition of claim 1, further comprising a water-solublepolymer having a cationic functional group.
 4. The liquid composition ofclaim 3, wherein the water-soluble polymer having a cationic functionalgroup is a polyamine compound or a polyamide compound.
 5. The liquidcomposition of claim 1, having a surface tension of 30 mN/m or lower. 6.The liquid composition of claim 1, further comprising: a fluorine-basedsurfactant, and a compound of Formula (2),HOR₁R₃C—[CH₂]_(n)—CR₂R₄OH   Formula (2) where R₁ and R₂ eachindependently are an alkyl group having 3 to 6 carbon atoms; R₃ and R₄each independently are an alkyl group having 1 to 2 carbon atoms; and nis an integer of 1 to
 6. 7. A recording method comprising: adhering aliquid composition onto a recording medium, and adhering an ink onto therecording medium, wherein the ink is a dispersion liquid comprisingwater and particles, wherein the particles comprise a colorant and havea negative charge and wherein the liquid composition comprises: anorganic acid ammonium salt of Formula (1), and water,

where R₁ is a hydroxyl group, a methyl group or a hydrogen atom; and R₂is a hydroxyl group or a methyl group wherein the liquid composition issuitable for agglutinating particles having a negative charge which aredispersed in a dispersion liquid.
 8. The recording method of claim 7,wherein the colorant is at least one selected from the group consistingof a self-dispersible pigment, a pigment coated with a resin, and apigment dispersed by a dispersant.
 9. A recorded matter comprising animage, wherein the image is recorded by a recording method comprising:adhering a liquid composition onto a recording medium, and adhering anink onto the recording medium, wherein the ink is a dispersion liquidcomprising water and particles, wherein the particles comprise acolorant and have a negative charge, and wherein the liquid compositioncomprises: an organic acid ammonium salt of Formula (1), and water

where R₁ is a hydroxyl group, a methyl group or a hydrogen atom; and R₂is a hydroxyl group or a methyl group wherein the liquid composition issuitable for agglutinating particles having a negative charge which aredispersed in a dispersion liquid.
 10. The liquid composition of claim 1,comprising 1 to 40 mass % of the organic acid ammonium salt, based on amass of the liquid composition.
 11. The liquid composition of claim 1,comprising 3 to 30 mass % of the organic acid ammonium salt, based on amass of the liquid composition.
 12. The liquid composition of claim 3,wherein the water-soluble polymer having a cationic functional groupcomprises at least one structural unit selected from the groupconsisting of an N,N-dialkylallylamine of Formula (C-1), an additionsalt of an N,N-dialkylallylamine of Formula (C-1), a diallylamine ofFormula (C-2), an addition salt of a diallylamine of Formula (C-2), adiallylamine of Formula (C-3), and an addition salt of a diallylamine ofFormula (C-3),

wherein R₁ and R₂ in Formula (C-1) are each independently an alkyl grouphaving 1 to 4 carbon atoms, and R₃ in Formulae (C-2) and (C-3) is ahydrogen atom or an alkyl group having 1 to 3 carbon atoms.
 13. Theliquid composition of claim 3, wherein the water-soluble polymer havinga cationic functional group has a weight-average molecular weight of 250to 3000 in a free state.
 14. The liquid composition of claim 3, whereinthe ignition residue of the water-soluble polymer having a cationicfunctional group is 5 mass % or less.
 15. The liquid composition ofclaim 3, wherein the ignition residue of the water-soluble polymerhaving a cationic functional group is 2 mass % or less.
 16. The liquidcomposition of claim 3, wherein the ignition residue of thewater-soluble polymer having a cationic functional group is 0.5 mass %or less.
 17. The liquid composition of claim 3, wherein thewater-soluble polymer having a cationic functional group comprises atleast one structural unit selected from the group consisting of anaddition salt of an N,N-dialkylallylamine of Formula (C-4), an additionsalt of an N,N-dialkylallylamine of Formula (C-5), a polyamide ofFormula (C-6), and a polyallylamine of Formula (C-7),

wherein R₄ and R₅ are each independently an alkyl group having 1 to 4carbon atoms, X⁻ is a counter ion selected from the group consisting ofCl⁻, Br⁻ and I⁻, and R₆ is a hydrogen atom or a methyl group.
 18. Theliquid composition of claim 17, wherein the water-soluble polymer havinga cationic functional group has a weight-average molecular weight of2000 to 15,000.
 19. The liquid composition of claim 6, comprising 0.01to 10 mass % of the compound of Formula (2).
 20. The liquid compositionof claim 6, wherein the compound of Formula (2) is2,4,7,9-tetramethyldecane-4,7-diol or2,5,8,11-tetramethyldodecane-5,8-diol.